Crop Profile for Cotton in Mississippi

Prepared March, 2002

For many years cotton has been Mississippi's leading row crop. Even with recent acreage reductions , Mississippi is still among the top five cotton producing states in the nation.

Records of acreage and production have been kept since 1866. The record highest yield was recorded in 1997 at 901 pounds of lint per acre. The record lowest yield per acre occurred in 1866 at 86 pounds of lint per acre. The record highest acreage occurred in 1930...4,136,000 acres. The record lowest acreage occurred in 1982...680,000 acres. The record high production occurred in 1937 at 2,692,000 bales. The record low production occurred in 1866 at 320,000 bales.

Typically Mississippi ranked second in acres behind Texas, third in yield per acre behind California and Arizona, and third in total bales produced behind Texas and California. Recently, due to acreage increases after boll weevil eradication, Georgia has exceeded Mississippi acreage and production. In 1998, cotton production ranked Number 4 in the United States and led all crops in Mississippi with cash receipts of $585 million.

In 1999, cotton in Mississippi was valued at $481.1 million, the average yield was 708 pounds of cotton per acre. There were 1,180,000 acres planted in 1999 producing 1.74 million bales.

Cotton requires large investments of capital, labor and management. However, cotton can return tremendous economic benefits to growers, the community and the state. There are also risks associated with the production of cotton. These risks, low prices and reduction is governmental support, resulted in growers reducing acreage. In 1995, Mississippi harvested 1,420,000 acres as compared to 970,000 acres in 1997 and some 916,000 acres in 1998.

In 2000, there were 1,300,000 acres planted which yielded 642 pounds per acre. In 2001, there were 1,800,000 acres planted which yielded 708 pounds per acre.

Production Regions

Cotton is primarily grown in three areas of the state: North Delta, South Delta and Hills with spotted acres in a few southern counties.

Worker Activities

Insect Scouting: Scouting for insects and monitoring plant development is the primary activity requiring pedestrian workers to enter cotton fields during the growing season. Scouting is performed by professional crop consultants and summer scouts (usually high school or college aged individuals) employed by these consultants, as well as by producers and industry fieldmen. Full time cotton scouts normally work in excess of 40 hours per week and much of this time is spent walking through cotton fields, counting insects and collecting information on plant development. Ideally, cotton is scouted twice weekly from emergence through the boll opening period. Full time cotton scouts are in direct contact with plants for a large portion of the day each work day of the growing season.

Irrigation: Approximately 21% of the cotton in Mississippi is furrow irrigated. Irrigation pipe must be placed in fields after all tillage operations are completed for the season and removed before harvest. This requires pedestrian workers to enter fields at least twice during the growing season to place and remove pipe. Workers may also be required to enter fields during the irrigation process, to make repairs and to manage the irrigation procedure. Workers performing such irrigation procedures may be in direct contact with plants, but this occurs during a limited portion of the season.

Hand Weeding: Hand weeding is uncommon, but is still performed occasionally by workers who are chopping weeds or 'spot spraying' with a hand carried sprayer. Workers performing such procedures are in direct contact with plants for a large portion of the time period during which the procedure is being performed, but this occurs during a limited portion of the season.

Tillage, Spraying, and Harvest: Individuals performing normal cultivation, spraying and/or harvest operations are operating motorized equipment, usually from an enclosed cab. Occasionally, it is necessary for equipment operators to dismount in the field to perform minor repairs, such as adjusting cultivators or unclogging spray nozzles. Workers are in direct contact with plants during the time that they are dismounted, but this represents only a small portion of the work day.

Integrated Pest Management

Cotton in Mississippi is attacked by more than a dozen different species of insect pests. Table 1 provides a list of the most common pests of cotton and a brief description of the damage they cause. Each of these pests is capable of causing economic yield loss, and some, such as the tobacco budworm, are capable of totally destroying a crop. Historically the bollworm/tobacco budworm complex has ranked as one of the most damaging pests of Mississippi cotton, but boll weevils, tarnished plant bugs, beet armyworms, fall armyworms, cotton aphids, and thrips have also caused high levels of damage in some years (Table 2).

Cotton growers may invest more than $500 to produce an acre of cotton, and all of this investment is potentially at risk to insect damage. The cost of controlling insects is one of the larger items of the crop production budget, annually averaging from $70 to over $100 per acre (Figure 1).

Integrated pest management (IPM) is practiced on all of Mississippi's cotton acreage. Producers utilize a variety of non-insecticidal management tools (Table 3) to limit the number of times that pests exceed economic thresholds and consequently require treatment with insecticides. However, timely judicious use of insecticides is an important component of cotton IPM. Recommendations for cotton insect management are published in the Cotton Insect Control Guide, which is revised annually to incorporate the latest technology and research. Table 4 lists the insecticides recommended for use in Mississippi cotton and the pests for which they are recommended.

Because pest populations can change quickly, cotton insect management is both information intensive and time sensitive. During the growing season, fields must be scouted every three to four days, and accurate estimates of pest populations must be determined by time consuming sampling procedures. Because of the time involved in making these counts, most Mississippi producers contract the services of a professional crop consultant, usually for a 'per acre' scouting fee, to monitor insect populations and make treatment recommendations.

During recent years there have been significant changes in Mississippi's cotton IPM system, and this system continues to evolve rapidly. These changes are occurring because of three major factors: transgenic Bt-cotton, boll weevil eradication, and new, more target specific insecticides.

In recent years from 70 to 80% of Mississippi's cotton acreage has been planted to Bt transgenic cotton varieties. Because Bt cotton is highly effective against tobacco budworm, fields planted to Bt varieties do not require treatment for this pest. Bt cotton is also effective against bollworms, but to a lesser degree, and Bt fields occasionally require treatment for control of bollworms. However, since Bt-cotton was first introduced in 1996, Bt fields have consistently required fewer treatments than non-Bt fields for caterpillar pests, while also sustaining less boll damage (Table 5).

Mississippi began boll weevil eradication efforts in 1997 in the Eastern portion of the state. In 2001, the Hill Region of Mississippi was in the 5th year of Boll Weevil Eradication Program and the South Delta and North Delta were in the fourth and third year, respectively. Although Mississippi has not yet achieved the goal of eradicating this pest, overall boll weevil numbers were extremely low in 2001, and no yield loss was attributed to boll weevils. Only 32% of the acres in the state required treatment for boll weevils and most of these treatments were applied late in the season, when they would be less likely to flare secondary pests. Progress of the boll weevil eradication effort has had a tremendous positive impact on Mississippi's Cotton IPM program, and has resulted in a sharp decrease in the number of insecticide applications applied by growers (Figure 2).

During the past several years a number of new insecticides, belonging to novel classes of chemistry, have been developed, or are being developed, for use in cotton. These include products such as spinosad (Tracer), indoxacarb (Steward), and thiamethoxam (Centric). While these products are quite effective against their primary target pests, they tend to control a narrower spectrum of pests than most of the older products. This can be advantageous, when there is a need to control only one pest, because the increased selectivity fosters conservation of beneficial insects. However, when there is a need to control multiple pest species, the need to tank mix multiple insecticides can offer distinct economic and ecological disadvantages.

Together, the broad adoption of transgenic Bt cotton, combined with the progress of the boll weevil eradication effort have resulted in significant reductions in the number of foliar sprays applied by Mississippi cotton producers (Figure 2). Unfortunately, this reduction in the number of foliar insecticide treatments has not provided a corresponding decrease in the per acre cost of cotton insect control (Figure 1). This is because of offsetting costs associated with 'technology use fees' for Bt cotton, assessment fees to fund boll weevil eradication efforts, and increased costs of newer insecticides. Still, boll weevil eradication and Bt cotton have had the very positive impacts of reducing the risks of insect induced yield losses, reducing overall use of insecticides, and reducing the physical and logistical effort that growers must devote to insect management.

One consequence of this new pest management system under which cotton is grown in Mississippi has been a shift in the overall pest complex. Pests such as boll weevils and tobacco budworms are of much less concern that they had been in past years, because of the direct effects of boll weevil eradication and Bt-cotton. The reduction in foliar sprays has also had an indirect effect in reducing outbreaks of secondary pests, such as cotton aphids and beet armyworms. However, pests such as tarnished plant bugs and stink bugs have thrived in this reduced spray environment and the number of treatments applied specifically to control these pests has increased.

Table 1: Insect Species Attacking Mississippi Cotton

Table 2: Ten-year summary of the top three most damaging cotton insects in Mississippi

Table 3: Some Non-insecticidal Components of Cotton IPM

Table 4: Insecticides recommended for use as foliar sprays in Mississippi cotton.

OP = organophosphate; C = Carbamate; CN = Chloro-nicotinyl; IGR = insect growth regulator; SPN = spinosyn; OX = oxadiazine; OC = organochlorine; P = pyrethroid

Table 5: Comparison of number of insecticide treatments and percent boll damage on Bt and non-Bt cotton in Mississippi, 6-year summary.

Figure 1. Estimated average cost per acre of controlling cotton insects in Mississippi (from nnual Cotton Insect Losses Estimates). These estimates include cost of insecticides, application costs, scouting fees, eradication program fees, and licensing fees for use of Bt cotton. The sharp increase in costs beginning in 1992 is due primarily to the development of high levels of insecticide resistance in tobacco budworm and other cotton pests. Since 1996, a number of new tools have been introduced that provide improved control of pests that are resistant to older insecticides. However, because these new tools are higher in cost and more target specific, their availability has had relatively little effect on the cost of insect control.

Figure 2. Average number of foliar insecticide treatments applied to Mississippi cotton fields, 1988-2000. The decline in number of spray applications is due to progress of the Boll Weevil Eradication Program and to widespread adoption of transgenic Bt-cotton. Treatments of ULV malathion applied as part of the Boll Weevil Eradication Program are not included in these estimates.

Cotton Insect Losses in Mississippi 2000

Table 16a. Mississippi Delta

Pest	acres infested	acres treated	# insect appls	Cost of 1 applic	cost/ acre	%red	Bales lost
Boll weevil	0	0	0.000	N/A	$0.00	0.000	0
Bollworm/budworm	812,000	410,000	1.161	$13.20	$15.33	1.900	32,142
Pink Bollworm	0	0	0.000	N/A	$0.00	0.000	0
Cotton Fleahopper	28,000	0	0.000	N/A	$0.00	0.002	29
Lygus	812,000	730,000	1.259	$7.20	$9.06	0.500	8,458
Cotton Leafperforator	0	0	0.000	N/A	$0.00	0.000	0
Spider Mites	160,000	55,000	0.088	$10.80	$0.95	0.059	1,000
Thrips, early season	812,000	510,000	0.817	$5.40	$4.41	0.700	11,842
Beet Armyworm	390,000	83,000	0.102	$11.70	$1.20	0.096	1,625
Fall Armyworm	580,000	120,000	0.148	$11.80	$1.74	0.429	7,250
European Corn Borer	20,000	0	0.000	N/A	$0.00	0.000	0
Stink Bugs	420,000	5,100	0.006	$7.20	$0.05	0.207	3,500
Grasshoppers	8,200	0	0.000	N/A	$0.00	0.001	17
Salt-marsh Caterpillars	129,000	17,000	0.021	$9.20	$0.19	0.016	269
Aphids	812,000	490,000	0.724	$6.80	$4.92	0.400	6,767
Bandedwinged Whitefly	510,000	85,000	0.136	$8.70	$1.18	0.031	531
Silverleaf Whitefly	0	0	0.000	N/A	$0.00	0.000	0
Soybean Loopers	140,000	37,000	0.046	$11.70	$0.53	0.017	292
Cabbage Loopers	0	0	0.000	N/A	$0.00	0.000	0
Western Flower Thrips	0	0	0.000	N/A	$0.00	0.000	0
Cutworms	812,000	110,000	0.135	$6.60	$0.89	0.080	1,353
Percent Lost	4.44		Est. yield/acre	680			Cost/ Acre
						Foliar insecticide	$40.46
Total Acres	812,000		Spray applications	4.643		At planting	$9.66
						Bt use fees	$21.20
			Cost + loss	$103,214,750		Eradication	$22.00
Total Bales lost	75,075					Scouting	$7.16
Bales lost in dollars	$21,621,480		Cost + loss/acre	$127.11		Total	$100.48

Table 16a. Mississippi Hills

Pest	acres infested	acres treated	# insect appls	Cost of 1 applic	cost/ acre	%red	Bales lost
Boll weevil	0	0	0.000	N/A	$0.00	0.000	0
Bollworm/budworm	475,000	105,000	0.354	$13.20	$4.67	2.800	27,708
Pink Bollworm	0	0	0.000	N/A	$0.00	0.000	0
Cotton Fleahopper	10,800	0	0.000	N/A	$0.00	0.000	0
Lygus	475,000	140,000	0.354	$5.55	$1.96	0.100	990
Cotton Leafperforator	0	0	0.000	N/A	$0.00	0.000	0
Spider Mites	320,000	19,000	0.052	$11.30	$0.59	0.067	667
Thrips, early season	475,000	142,000	0.359	$4.60	$1.65	0.500	4,948
Beet Armyworm	140,000	13,000	0.027	$11.90	$0.33	0.029	292
Fall Armyworm	187,000	37,000	0.078	$13.25	$1.03	0.472	4,675
European Corn Borer	0	0	0.000	N/A	$0.00	0.000	0
Stink Bugs	350,000	33,000	0.069	$7.40	$0.51	0.221	2,188
Grasshoppers	43,000	10,000	0.021	$7.60	$0.16	0.018	179
Salt-marsh Caterpillars	80,000	2,000	0.004	$8.30	$0.03	0.017	167
Aphids	475,000	41,000	0.095	$6.50	$0.62	0.210	2,078
Bandedwinged Whitefly	220,000	21,500	0.059	$9.95	$0.59	0.093	917
Silverleaf Whitefly	1,000	300	0.001	$19.50	$0.01	0.011	104
Soybean Loopers	75,000	10,000	0.021	$12.30	$0.26	0.047	469
Cabbage Loopers	0	0	0.000	N/A	$0.00	0.000	0
Western Flower Thrips	0	0	0.000	N/A	$0.00	0.000	0
Cutworms	475,000	42,000	0.088	$6.90	$0.61	0.100	990
Percent Lost	4.69		Est. yield/acre	630			Cost/ Acre
						Foliar insecticide	$13.02
Total Acres	475,000		Spray applications	1.582		At planting	$8.09
						Bt use fees	$24.40
			Cost + loss	$48,969,103		Eradication	$23.40
Total Bales lost	46,370					Scouting	$6.07
Bales lost in dollars	$13,354,500		Cost + loss/acre	$103.09		Total	$74.98

Insecticides recommended for use in Mississippi cotton and the primary pests for which they are recommended are listed in Table 4. Tables 6A-6D summarize the relative use of these insecticides during the past four growing seasons, 1998 through 2001. Examination of these tables shows that acephate, dicrotophos, and the pyrethroids (collectively) were the most commonly used insecticides. The use and significance of each of the insecticides recommended for use in Mississippi cotton is discussed below.

Foliar Applied Insecticides:

Acephate (Orthene): For the past several years acephate has been the most commonly used individual foliar insecticide in Mississippi cotton. In 2001 Mississippi growers applied approximately 1.4 applications of acephate per field, which constituted one-third of all foliar sprays.

The most important use of acephate is for control of tarnished plant bug. Acephate belongs to a different sub-class of chemistry than most other organophosphates used on cotton, and it is one of the few 'older' insecticides to which plant bugs have not developed high levels of resistance. Acephate is used to control plant bugs throughout the growing season. Use rates in the range of 0.25 to 0.5 lbs. Ai./acre are usually effective during early season, but rates of at least 0.5 lbs ai/acre are required during mid to late season. Successful control of heavy, mid to late season plant bug infestations requires repeated applications applied approximately 5 days apart.

In addition to being used as an at-planting seed treatment and as an in-furrow treatment for thrips control, acephate is also commonly used as a foliar treatment to control thrips on seedling cotton. Rates of 0.2 to 0.25 lbs ai/acre are effective against all species of thrips, except the western flower thrips. Acephate is also recommended for control of cutworms, stink bugs, and whiteflies. Acephate is especially useful as a tank mix partner with pyrethroid insecticides to control mixed populations of bollworms and plant bugs.

Dicrotophos (Bidrin): Dicrotophos is one of the most frequently used cotton insecticides. In 2001, Mississippi cotton received an average of 0.53 applications per field, which represented 12.9% of all foliar insecticide treatments. The relative importance of dicrotophos has increased in recent years, because plant bugs and stink bugs are becoming more important in post-eradication/Bt cotton systems.

Tarnished plant bugs are the primary target of most dicrotophos applications. However, in the Delta Region, the performance of dicrotophos is somewhat erratic because of resistance. Still, dicrotophos remains one of the more important treatments for tarnished plant bug. Rates of 0.25 to 0.33 lbs ai/acre may provide effective control during early season, especially in the Hill Region, but the 0.5 lb ai/acre rate is required during mid to late season. Multiple applications applied approximately 5 days apart are required to control heavy mid to late season plant bug infestations. Dicrotophos is also quite effective against stink bugs and is a good choice for control of mixed populations of plant bugs and stink bugs during mid to late season.

Dicrophos is one of only three products recommended for control of cotton aphids. A single, properly timed application will usually provide adequate control of aphid infestations, but overall efficacy is somewhat less than that of products like carbofuran or thiamethoxam. Dicrotophos is a cost-effective treatment for control of mixed infestations of plant bugs and aphids. It is also recommended for control of thrips on seedling cotton, and is useful against a number of occasional pests.

Dimethoate: Dimethoate is an organophosphate insecticide that has declined in use, primarily because of resistance in aphids and tarnished plant bugs. Currently, it is only recommended for control of thrips on seedling cotton at a rate of 0.2 lbs ai/acre. It is not commonly used.

Methyl Parathion: As the treatment of choice against boll weevils, this organophosphate insecticide was once the most commonly used treatment in Mississippi cotton. However its use has plummeted since the initiation of boll weevil eradication efforts. Currently it is recommended only for control of stink bugs, but it receives very little use. However, methyl parathion is one of the most cost-effective treatments for stink bugs, and it continues to be important for this reason.

Methamidophos (Monitor): Methamidophos is a relatively expensive organophosphate insecticide, and because of this, it is rarely used. It is recommended primarily for control of whiteflies, which are occasional pests. It is also effective against thrips and plant bugs. The 0.2 lb. Ai/acre rate is effective against thrips, but the 0.5 lb. Ai./acre rate is required to best control plant bugs and whiteflies.

Profenophos (Curacron): At one time profenophos was widely used for control of tobacco budworms and tarnished plant bugs, as well as other pests. However, its use has declined greatly in recent years due to resistance in tobacco budworm and plant bug populations, as well as to wide spread planting of Bt cotton and availability of new, more effective caterpillar materials.

In 2001 Mississippi cotton fields received only 0.08 applications of profenophos, which represented only 2% of all foliar insecticide sprays.

Profenofos is still recommended for control of budworm/bollworm and plant bugs, but its use is limited due to the factors previously mentioned. It is also labeled and recommended for control of spider mites and fall armyworms, but it is generally less effective than other labeled products against both pests. Currently the key value of profenophos is that it is an economical choice for use against mixed populations of bollworms and plant bugs, or against mixed populations of bollworm/budworm and a building spider mite infestation. Use rates range from 0.25 lbs ai/acre (as an ovicide for control of bollworm/budworm eggs) to 1.0 lbs ai/acre (larvicide rate).

Propargite (Comite): Propargite, which is a specific miticide, is rarely used in Mississippi, because of cost and because spider mite outbreaks are uncommon. This organophosphate miticide is also difficult to obtain, because it is not commonly stocked by distributors. However, because it is one of the more effective products for use against mites, it would become extremely important in the event of a severe mite outbreak.

Oxamyl (Vydate): Oxamyl is a carbamate insecticide. Its overall use has declined in recent years because the boll weevil eradication program has eliminated one of two pests for which it was used. Currently oxamyl is primarily used for control of tarnished plant bugs at a recommended rate of 0.25 to 0.33 lbs. Ai./acre. In 2001 Mississippi cotton received an average of 0.14 applications of oxamyl, which represented 3.4% of all foliar sprays. Because it belongs to a different class of chemistry than other plant bug materials, Oxamyl plays an important role in plant bug resistance management.

Methomyl (Lannate): Methomyl is a carbamate insecticide that was commonly used as an ovicide and as a larvicide against bollworm/tobacco budworm. However, this product is rarely used today because of widespread planting of Bt cotton and availability of more effective caterpillar treatments. Currently methomyl is recommended as an ovicide (0.25 lbs ai/acre) to control bollworm and tobacco budworm eggs. It is recommended at 0.45 lbs ai/acre for control of larvae of bollworm, tobacco budworm, and fall armyworm. When applied at this rate, methomyl has a tendency to cause mild phytotoxicity (reddening of leaves), and this is another factor that limits its use.

Thiodicarb (Larvin): Thiodicarb is a carbamate insecticide that was commonly used as an ovicide (at 0.25 lbs ai/acre) and as a larvicide (at 0.6 to 0.9 lbs ai/acre) against bollworm/tobacco budworm and other caterpillar pests. This product is rarely used today because of widespread planting of Bt cotton and availability of newer caterpillar treatments. Currently thiodicarb is recommended as an ovicide to control bollworm/budworm eggs in non-Bt cotton. It is also recommended for control of bollworm/budworm larvae and for control of loopers and armyworms. Thiodicarb continues to be one of the most effective treatments for use against larger, 'escaped', bollworm/budworm larvae. Thiodicarb is not 'rain fast' and requires several rain free/irrigation free days for maximum efficacy. This lack of rain fastness is another factor that limits its use.

Imidacloprid (Provado): Imidacloprid is a chloro-nicotinyl insecticide that has been available for several years. It is recommended for control of cotton aphids and tarnished plant bugs at a rate of 0.047 lbs ai/acre. However, imidacloprid receives little use in Mississippi cotton because of its relatively high price. In 2001 Mississippi fields received approximately 0.09 applications of imidacloprid per field, which represented 2.2% of all foliar sprays.

Thiamethoxam (Centric): Thiamethoxam is a chloro-nicotinyl insecticide that was first labeled in 2001. At the recommended use rate of 0.047 lbs ai/acre, it is effective against cotton aphids and tarnished plant bugs, as well as whiteflies. Mississippi cotton fields received approximately 0.14 applications of thiamethoxam in 2001, which constituted approximately 3.4% of all foliar sprays. Because it provides good control of aphids and plant bugs and is reasonably priced, the relative use and importance of thiamethoxam will likely increase.

Tebufenozide (Confirm): Tebufenozide is an 'insect growth regulator' that is recommended for control of beet armyworms. It is very effective against this pest but has little activity against other caterpillar pests. Consequently, it is rarely used.

Methoxyfenozide (Intrepid): Methoxyfenozide is an 'insect growth regulator' that is recommended for control of beet armyworms, fall armyworms, and loopers. At the recommended use rate of 0.06 to 0.1 lbs ai/acre it is a very effective, economical treatment for these pests. Because of its wider spectrum of activity, methoxyfenozide has displaced tebufenozide in cotton. Methoxyfenozide also has activity against bollworm/tobacco budworm, but the rates required to control these pests are cost prohibitive. Although this product is rarely used in most years, it is a very important component of the cotton insecticide arsenal because it provides cost-effective control of several important occasional pests.

Pyriproxyfen (Knack): Pyriproxyfen is an 'insect growth regulator' that is recommended for control of silverleaf whiteflies at a rate of 0.054 to 0.067 lbs ai/acre. It is a very expensive treatment that is rarely used because silverleaf whitefly infestations are uncommon in Mississippi. Still, this pest does occasionally occur in the state, and pyriproxyfen would become a very important product in the event of an outbreak of silverleaf whiteflies.

Spinosad (Tracer): Spinosad is a relatively new insecticide that is used solely to control caterpillar pests. It belongs to the class of chemistry known as spinosyns. Use rates range from 0.067 to 0.089 lbs ai/acre (the 0.045 lbs ai/acre rate is not recommended, except as a tank mix partner). Spinosad provides good control of tobacco budworms, as well as most other caterpillar pests, and this makes it an important tool in the production of non-Bt cotton. It is rarely used in Bt cotton. In 2001, Mississippi cotton fields received approximately 0.21 applications of Tracer, but only 20% of the acres were planted to non-Bt varieties. In 2000 Mississippi fields received an average of 0.58 applications of Tracer. Tracer is relatively benign to most beneficial insects.

Indoxacarb (Steward): Indoxacarb was first labeled for use in cotton in 2001. It belongs to the oxadiazine class of insecticides. At the recommended rate of 0.09 to 0.11 lbs ai/acre it is effective against most caterpillar pests. Because it is effective against tobacco budworms, the primary use niche for indoxacarb is in non-Bt cotton. In 2001 Mississippi cotton fields received approximately 0.13 treatments of indoxacarb, which represented 3% of all foliar sprays. However, overall use of this product may well increase, especially if the percentage use of Bt cotton declines following successful eradication of the boll weevil. Indoxacarb also has activity against tarnished plant bug. Although it is not recommended for use against plant bugs as a primary target pest, this is an important advantage when growers need to control mixed infestations of caterpillars and tarnished plant bugs.

Dicofol (Kelthane): Dicofol is an organochlorine miticide. It is rarely used in Mississippi cotton, primarily because mite outbreaks are relatively uncommon. However, in the event of severe spider mite outbreaks it would become more important.

Pyrethroids: The pyrethroids currently recommended for use in Mississippi cotton are: bifenthrin (Capture), cyfluthrin (Baythroid), cyhalothrin (Karate-Z), cypermethrin, (Ammo), deltamethrin (Decis), esfenvalerate (Asana XL), fenpropathrin (Danitol), tralomethrin (Scout X-Tra), and zetamethrin (Fury). These are discussed collectively because of their broad similarities. Collectively, the pyrethroids are one of the most important, most commonly used insecticides. In 2001 Mississippi cotton fields received an average of 0.98 applications of pyrethroids, which represented 25.8% of all foliar insecticide sprays.

Pyrethroids are broad spectrum insecticides, providing control of a number of important pests. However, their overall utility has eroded in recent years due to development of high levels of pyrethroid resistance in cotton aphids, tobacco budworms, and tarnished plant bugs (plant bug resistance to pyrethroids is primarily in the Delta Region).

Currently the most important use of pyrethroids is for control of bollworms in Bt cotton. Pyrethroids are highly effective against bollworms and are more economical than the available alternatives. Pyrethroids are no longer recommended for control of tobacco budworms, because of high levels of resistance, but they continue to be useful in non-Bt cotton, against populations that are known to be primarily bollworms. Some pyrethroids are useful in the control of fall armyworms.

Pyrethroids are also recommended for control of cutworms and are often applied at planting in fields that have a high potential for experiencing cutworm problems. Because pyrethroids are effective against cutworms at very low rates, they are more economical than the alternatives. The recent increase in the utilization of herbicide tolerant cotton and the resulting increase in reduced till/no-till planting has resulted in increased potential for cutworm infestations. Pyrethroids are also recommended for control of stink bugs, a pest that is increasing in importance due to boll weevil eradication and wide spread planting of Bt cotton. Pyrethroids are an especially cost-effective treatment for mixed infestations of bollworms and stink bugs, which can occur in Bt cotton during mid to late season.

Bifenthrin (Capture) is a somewhat unique pyrethroid that also has activity against spider mites and is recommended for control of mites. In past years bifenthrin was also recommended for control of cotton aphids, but development of pyrethroid resistance in aphids has nullified this use. Fenpropathrin (Danitol) is recommended primarily in a tank mix with acephate for control of silverleaf whiteflies, which currently is a very minor use in Mississippi. Fenpropathrin also has activity against spider mites.

Soil Applied Insecticides:

Soil applied insecticides are applied at planting, primarily for control of thrips. These treatments may be applied as seed treatments, or as in-furrow granules or in-furrow sprays.

Aldicarb (Temik): Aldicarb, which is a carbamate, is the most commonly used soil applied insecticide. This is because of its excellent, long-lasting activity against thrips and because, when used at adequate rates, it provides good suppression of nematodes. In 2001, approximately 59% of Mississippi cotton fields were treated with aldicarb. Recommended use rates range from 3.5 to 5 lbs. Ai/acre. Aldicarb also provides early season suppression of plant bugs and cotton aphids, but it does not control cutworms.

Acephate (Orthene): When applied as a seed treatment, acephate (organophosphate) will provide thrips control in seedling cotton for 7 to 10 days after emergence. However, acephate is also recommended as a liquid in-furrow spray or as the granular formulation know as Payload at a rate of 1.0 lbs ai/acre, and this rate will provide longer thrips control, as well as suppression of plant bugs and cutworms.

Imidacloprid (Gaucho): Imidacloprid is a chloro-nicotinyl insecticide that is offered as a seed treatment. It provides effective control of thrips on seedling cotton and was used on approximately 9% of Mississippi cotton fields in 2001.

Thiamethoxam (Adage): Thiamethoxam (chloro-nicotinyl) is sold as a seed treatment known as Adage for control of thrips on seedling cotton. This new product provides effective control of thrips for two to three weeks following emergence. It will also control aphids on seedling cotton. Use of thiamethoxam is likely to increase in future years, but will be limited somewhat by the lack of nematode control.

Table 6A: Use of individual foliar applied insecticides on cotton in Mississippi, 2001¹.

Compiled from a survey of 120 Mississippi Cotton Fields (69 Bt fields and 51 non-Bt fields) which received a total of 496 foliar insecticide treatments.

¹Does not include foliar applications of ULV malathion applied as part of the boll weevil eradication program.

Table 6B: Use of individual foliar applied insecticides on cotton in Mississippi, 2000¹.

Compiled from a survey of 59 Mississippi Cotton Fields (34 Bt fields and 25 non-Bt fields) which received a total of 183 foliar insecticide treatments.

¹Does not include foliar applications of ULV malathion applied as part of the boll weevil eradication program.

Table 6C: Use of individual foliar applied insecticides on cotton in Mississippi, 1999¹.

Compiled from a survey of 93 Mississippi Cotton Fields (55 Bt fields and 38 non-Bt fields) which received a total of 317 foliar insecticide treatments.

¹Does not include foliar applications of ULV malathion applied as part of the boll weevil eradication program.

Table 6D: Use of individual foliar applied insecticides on cotton in Mississippi, 1998¹.

Compiled from a survey of 133 Mississippi Cotton Fields (78 Bt fields and 55 non-Bt fields) which received a total of 848 foliar insecticide treatments.

¹Does not include foliar applications of ULV malathion applied as part of the boll weevil eradication program.

BOLL WEEVIL

Historically, the boll weevil was the most important insect pest of Mississippi cotton. Boll weevil was considered a key pest of cotton, because the early season treatments that were necessary to control boll weevil destroyed beneficial insects and thus "flared" secondary pests, such as tobacco budworms and aphids.

As of the end of the 2001 growing season, statewide eradication efforts have reduced boll weevil numbers to extremely low levels, and it appears that complete eradication will be achieved within the next two years. Mississippi cotton growers no longer spray for boll weevils themselves, and only 32% of Mississippi's cotton acreage was treated by the Boll Weevil Eradication Program (BWEP) in 2001. Fifty-one percent of Mississippi fields remained weevil free for the entire season, and no yield loss was attributed to boll weevils in 2001. Therefore, the primary concern for Mississippi cotton with respect to the boll weevil is to complete the BWEP and to successfully maintain eradication, once it is achieved. The Hill Region of Mississippi passed a 10-year eradication maintenance referendum in 2001 and the remaining two regions of the state will vote on maintenance programs during the next two years.

A successful maintenance program will require the continuation of a vigorous pheromone trapping program on all cotton in the state. This is necessary so that any re-infestations of boll weevils can be promptly detected and eliminated before they have a chance to spread. Successful eradication maintenance will also require continued education of growers and scouts, so that they will be able to recognize and promptly report the presence of boll weevils and/or boll weevil damage in their fields. Successful eradication maintenance also requires continued, ready access to insecticides that are effective against boll weevils and can be used to eliminate any re-infestations that do occur. Because of logistical, environmental, and cost considerations, Malathion ULV has been the primary insecticide used in the BWEP, but a number of other insecticides are also effective against boll weevils.

The damage done by the pest: Weevils puncture squares and bolls with their snouts to feed and to lay eggs. If a weevil puncture is topped with a whitish or brown bump or "wart", it is an indication that the female has laid an egg in the hole and sealed the puncture to protect the egg. This gluey substance is white on newly sealed egg punctures, but browns with age. Some weevil punctures will not have this sealer, particularly if the insect merely feeds. Normally, the weevil, prefers squares and makes only one egg puncture per square, but it will select young bolls in many cases. Weevil damage will range from one or two locks per boll to complete boll loss since many punctured squares or young bolls will drop off after the pest drills the hole.

Life cycle: Total time from egg to adult ranges from 16 to 25 days; egg - two to three days; larva - five to eight days; pupa - three to five days; newly emerged adult ("callow" adult) - one day; feeding adult - five to eight days before egg laying. Adult females lay an average of 30 eggs each day for approximately 10 days. Each generation normally multiplies tenfold. In a typical field boll weevils numbers will increase at a rate of about two and one-half times each week - about the same rate of increase as the squares in the field.

Boll weevils spend the winter in a semi-dormant state (reproductive diapause) in hardwood ground cover, such as patches of woods. During mild winters, they also can survive in grass or other cover. Usually four generations of weevils occur during the season. When daytime temperatures begin to rise above 70 degrees weevils begin emerging. Emergence may continue from before cotton is big enough to support the pests until July, peaking normally in May and June.

While there are not always clear-cut steps in the emergence of over-wintered weevils, the first adult in-field generation can begin emerging about a week after the first white bloom, with others following at about three-week intervals. Climate and weevil food supply can greatly influence peaks in weevil populations.

Critical timing of control measures: Treatment for suppression of overwintering boll weevils is determined using pheromone traps. If trap captures the week prior to squaring exceeds four weevils per trap per week, a suppression spray may be needed, and a second treatment may be required if populations are high. These 'pin-head square sprays' are highly effective in eliminating a large portion of the overwintered generation of boll weevils before they have an opportunity to reproduce. After cotton begins to square, applications of insecticides to control the boll weevil will normally be applied when square damage levels reach specified treatment thresholds. Successful control requires the application of a series of three to six treatments applied on a three to four day schedule. This spray schedule is necessary because immature stages of the boll weevil are inside squares and bolls where they are protected from exposure to insecticides. The objective is to control newly emerged adult boll weevils before they have the opportunity to reproduce.

Yield losses and prevalence: In the absence of effective control efforts boll weevils have the ability to completely destroy a cotton crop. Historically, 100% of Mississippi's cotton fields were infested by boll weevils and growers applied multiple, close interval insecticide treatments to keep boll weevil populations in check. Despite this heavy insecticide use, yield losses were still significant. Before the BWEP was initiated in 1997 the estimated annual yield loss attributed to boll weevils ranged from 0.2% to 6.5%. Yield losses were historically higher following milder winters, which allowed higher survival of overwintering weevils. Yield losses also were historically higher in the Hill region of the state than in the Delta region and often exceeded 5% in the Hills. Beginning in 2000, and continuing in 2001, the eradication effort had reduced boll weevil populations to such low levels that no yield loss was attributed to this pest.

Chemical Control Information:

Control Alternatives:
Pheromone traps and the Boll Weevil Eradication Program are the primary alternatives for controlling the boll weevil. Originally started in North Carolina and Virginia in 1978, the Boll Weevil Eradication Program (BWEP) program has since been implemented by most of the other cotton producing states in the southeastern United States. The implementation of BWEP is expected over the rest of the state in the next eight years. The primary components of BWEP are timely applications of malathion and intensive use of boll weevil pheromone traps. It is a very intensive program that requires close monitoring of boll weevil populations in coordination with producers.

Cultural Control Practices: Early-maturing varieties may escape damage by late season generations when boll weevil populations are highest.

Biological Controls: There are few effective parasitoids or predators of boll weevils in the Mid-South. Fire ants are known to prey on developing weevils in fallen squares, but this predation does not provide effective biological control.

COTTON BOLLWORM and TOBACCO BUDWORM

The bollworm and tobacco budworm species comprise what is commonly referred to as the Heliothine complex. Both species belong to the Noctuidae family of insects and attack cotton in a similar fashion. In Arkansas, bollworm and tobacco budworm populations vary greatly from south to north. The overall population levels of the Heliothine complex are higher in south Arkansas. Both species occur as pests of cotton each year. Of the two species, the bollworm is a more frequent problem whereas the tobacco budworm is more difficult for producers to control. Tobacco budworms are resistant to many insecticides especially those in the pyrethroid class of insecticides. Over the past 10 years, the tobacco budworm has become a more difficult insect to control.

The damage done by the pests: The most obvious damage is feeding on squares and bolls, but bollworms and budworms can also reduce yields through secondary damage. Feeding damage often provides entry for disease organisms, which can lead to boll rot. This usually occurs in irrigated cotton, but it can occur in wet periods after rainfall.

Life cycle: Egg - three to five days; larva - 12 to 15 days spent feeding on cotton; pupa - 12 to 15 days, resting in top two to four inches of the soil; adult - moths emerge from pupae and begin laying eggs in 3 to 12 days. The development of one complete generation thus may require from 27 to 35 days. Female bollworm moths can lay from 250 to 1,500 eggs. In a normal season, there usually are about five generations, but some of these are spent on plants other than cotton. Normally, only two or three generations inflict important damage on cotton.

These worms overwinter in the soil, in the pupa stage, after going through a preparation phase. Moth migration is common and moths may move many miles. Expect the first generation in early spring. At that time, the pests develop on legume crops, such as crimson clover of alfalfa. The second generation of bollworms prefer corn; when found in corn this insect is called the corn earworm. Third generation worms generally are the first infestation for cotton, but insects also will infest corn or grain sorghum if these crops are present. If corn or milo is close by, the third generation may leave and migrate into cotton. Also, roadside plants such as evening primrose attract bollworms.

Light intensity, rather than the time of day, triggers bollworm and budworm behavior. On an average day, light intensity of 800 footcandles, known to affect moth feeding, is reached at 4 to 5 p.m. Moths feed on nectar from flowers and the nectary glands of cotton. Aphid honeydew also is an attractive food, as well as water droplets. By 7 p.m., if the light intensity is around 28 footcandles, moths are triggered into laying eggs, which may continue until 9 to 10 p.m. Some eggs are laid in blooms so newly emerged larva may feed inside the bloom. Blossoms may fold over the pests, so insecticide coverage failure can occur. Newly hatched larvae may feed on leaves the first day before attacking squares andbolls.

Critical timing of control measures: Before bloom, treatment is recommended if the number of larvae reaches or exceeds 8 per 100 plants. From first bloom through cutout the threshold is 4 larvae per 100 plants but increases to 8 per 100 plants after cutout. On non-Bt cotton it is extremely important to target applications against larvae that are no longer than 1/4 inches down to egg hatch. Thresholds for Bt cotton are similar, except that only larvae greater than 1/8 of an inch in length are included in the count (smaller larvae may be controlled by the Bt toxin, but larvae that have attained this 1/8 inch size are likely to survive on Bt).

Yield Losses and Prevalence: Historically, the bollworm/tobacco budworm complex has been one of the most damaging and most costly insect pests of Mississippi cotton. Tobacco budworm has the potential to totally destroy a field, and this occurred in a large number of fields in Mississippi's Hill Region in 1995. All Mississippi fields are infested by this pest complex, however infestation levels and damage have declined somewhat in recent years due to wide spread adoption of transgenic Bt cotton. Still, if the costs of the "technology use fee" are considered, the cost of controlling these pests remains high. Statewide yield losses attributed to bollworm/budworm have ranged from 1.9 to 8.0% during the past 10 years, but a 23% yield loss was reported for the Hill Region in 1995. Costs of bollworm/budworm control reached approximately $82 per acre in the Hill Region that year. Statewide control costs for this pest complex have ranged from $34 to $57 per acre during recent years.

Chemical Control Information - Ovicides

Chemical Control Information - Larvae and Adults

Control Alternatives: Emamectin benzoate (Denim), which is currently under developed and has been used under Section 18 Emergency Exemptions, is effective against bollworm and tobacco budworm, as well as most other caterpillar pests. Transgenic Bt cotton was planted on approximately 80% of Mississippi's cotton acreage in 2001.

Cultural Control Practices: Transgenic B.t. cotton varieties currently provide 100% control of tobacco budworms and approximately 60 to 70% control of bollworms. Early maturing varieties of non-Bt cotton may escape damage from the last, and heaviest, generations of budworm and bollworm. Varieties exhibiting the 'high-glanding trait' possess some resistance to budworm and bollworm. Smooth leaf varieties are less attractive to ovipositing moths than are varieties with more hairy leaves. Fields planted using no-till methods often benefit from enhanced biological control of bollworm/budworm due to coincidental conservation of fire ants, which are important predators of bollworm/budworm eggs and larvae. Fields planted using conventional tillage methods are usually tilled in the fall or early spring, before bollworm/budworm pupae overwintering in the field have a chance to emerge. This tillage causes high mortality levels in that portion of the bollworm/budworm population overwintering in cotton fields.

Biological Controls: Naturally occurring biological control is the most important method of controlling tobacco budworm. Despite its damaging and costly history as a pest of cotton, tobacco budworm is most appropriately considered a secondary pest (bollworm is more appropriately considered a major pest, because of the movement of large numbers from corn). Tobacco budworm has a large number of predators and parasitiods, which will often prevent it from reaching damaging levels, unless they are destroyed by early season insectide treatments applied to control other pests. Most of these will also attack bollworm and aid in suppressing bollworm populations as well. Consequently, monitoring beneficial insect populations and considering their presence and abundance in treament decisions can aid greatly in management of bollworm and budworm.

THRIPS

Thrips are a common (i.e., yearly) problem for most cotton producers in the Mid-South. Thrips infest cotton in the young seedling stage and severe thrips damage can stunt growth and reduce yield potential. As a result, most cotton is treated with an in-furrow insecticide to prevent the development of damaging populations and consequently thrips are rarely a devastating problem. cotton.

The damage done by the pest: Thrips have punch and suck or piercing sucking mouthparts, which allow them to punch a hole in a leaf cell, insert their maxillary stylets, and suck up the cellular fluids. When it occurs on leaves and other plant parts that have already expanded, this type of injury causes little or no significant harm to the plant. However, when such injury occurs within the terminal bud, on tiny developing leaves and fruiting structures, the effect can be quite different.

When thrips feed on the young undeveloped leaves within the terminal bud, the resulting damage is magnified as those leaves develop and expand. This is because the damaged tissue fails to develop properly, while undamaged tissue continues to grow. After prolonged feeding or feeding by high numbers of thrips, seedlings have a ragged appearance, with visible silvery feeding sites on cotyledons and terminal leaf tissue. Over time these silver areas will become brown in color. Heavily injured leaves usually have a crinkled, tattered appearance and often curl upward at the margins. Seedlings exhibiting this type of injury are often described as "possum eared cotton". Heavy thrips populations can stunt growth, cause death of the terminal bud (resulting in "crazy cotton"), delay fruiting and reduce stand. Thrips damage often is magnified by cool weather or drought, which can slow plant growth and/or lengthen thrips' developmental time and increase the probability of seedling damage. Seedlings that emerge under warm, favorable growing conditions are much less susceptible to thrips injury than are those that emerge under conditions conducive to slow seedling development.

Life cycle: Egg - four days; larva - six days, molting twice; pupa - four days; egg to adult - 14 days average. These pests overwinter in the pupa stage in plant trash. They begin reproducing in early spring in non-cotton host plants, such as grains, early blooming weeds, and legumes. Once the early host plants toughen, thrips move quickly into cotton fields. In many areas of the Cotton Belt, thrips migrate into cotton about the time wheat is cut. When the pests migrate, late-planted cotton is one of their chief targets since the crop is tender and offers easy feeding.

Critical timing of control measures: Of the various methods used to control thrips, most must be applied on a preventative basis, before there is any evidence that a potentially yield limiting infestation of thrips has occurred. Thrips are the only cotton insect pests for which such preventative treatments are recommended. However, because of the nature of thrips migration into cotton fields and the nature of the cotton plant=s susceptibility to thrips, these preventative, at planting type treatments generally are recommended over the "no at planting treatment and spray as needed" approach in most cases. This is especially true for fields planted under cool or adverse growing conditions, because slow plant growth results in a wider window of susceptibility to thrips injury. Fields planted during late season, under warm ideal growing conditions are less likely to benefit from in-furrow, systemic insecticides.

Regardless of whether or not a field is treated with a soil or seed applied insecticide at planting, all fields should be scouted carefully for thrips until plants reach the four-leaf stage. Fields should be scouted at least every five days, but a three to four day schedule is even more effective. There are a number situations that can cause soil applied treatments to fail, and frequent scouting, combined with prompt application of supplemental foliar sprays can prevent yield limiting injury.

Yield losses and Prevalence: Thrips infest every acre of Mississippi cotton every year, but the degree of infestation varies considerably, depending on the season. The ultimate impact of thrips injury on yield is highly variable. Cotton that is planted under good growing conditions can withstand relatively heavy infestations without suffering yield loss. However severe thrips injury can result in substantial yield reductions. In 14 trials conducted in Mississippi between 1994 and 2000 the yield losses in the untreated check compared to the most effective treatment in the trial ranged from 10 to 271 lbs. of lint/acre. The average yield increase for the standard treatment (aldicarb) was 114 lbs of lint. Average yield losses attributed to thrips range from 0.1 to 0.6%, but these losses would be much higher in the absence of effective treatments.

Chemical Control Information:

Control Alternatives: A number of other insecticides will control thrips when applied as foliar treatments, but are not recommended because of economic or resistance management concerns. Also, foliar treatments are generally less effective in preventing yield loss than 'at-planting' treatments. Thiamethoxam (Adage) is very effective as a seed treatment for control of thrips. Thiamethoxam has recently been added to the Mississippi Cotton Insect Control Guide.

Cultural Control Practices: Fields planted during late season, into warm, moist soil with good growing conditions are less likely to benefit from in-furrow systemic insecticides than are fields planted under cool, adverse growing conditions. Some cotton varieties are more tolerant than others to thrips injury.

Biological Controls: Thrips are attacked by a number of predators, including the insidious flower bug, but their importance in the population dynamics of thrips on seedling cotton is unknown.

PLANT BUGS

Tarnished Plant Bug (TPB) is an important pest of cotton throughout Mississippi. However, it is relatively more important in the Delta Region of the state than in the Hills. TPB is considered a "key" pest of cotton because it often reaches treatable levels during the early portion of the season and insecticides applied to control these early plant bug infestations often flare populations of secondary pests, such as aphids or tobacco budworms. Before boll weevil eradication the importance of TPB as a key pest of cotton was overshadowed by the boll weevil. Due to the success of the boll weevil eradication effort and the wide spread adoption of Bt-cotton, the importance of TPB has increased in recent years. Not only have boll weevils and budworm/bollworm declined in importance, but the reduction in sprays applied to control these pests results in less coincidental control of TPB. As a result, the number of sprays required specifically to control TPB has increased in recent years, especially in the Delta.

The damage done by the pest: All plant bugs have piercing mouthparts used to suck plant juices. Pinhead squares are primary targets. Soon after damage, the small squares turn brown and shed. Pre-squaring cotton is not safe though, since these insects attack growing portions of the plants and inflict serious damage even before square formation. Plant bugs, in this case, damage the stems and the young, tender terminals of the cotton plant. This injury can be serious enough to cause the plants to shift into exaggerated growth, with cotton branches becoming long and whip-like. In many cases, the cotton never really recovers. Damage symptoms sometimes cause "crazy cotton" where plants are severely distorted and stay in a pattern of fruitless growth for several weeks.

Severe infestations often develop quickly because these pests may build up into a massive population on another host, such as spring blooming weeds along roadsides. When the first host plant is cut or becomes tough, plant bugs migrate quickly into cotton and growers are faced with a full-blown plant bug problem just a day or two after checking clean fields. Flowers also are attacked by some plant bug species, causing warty growths on flower petals and brown spots on stamens and pistils. Plant bugs lay eggs inside cotton stems near the top of the plant. The pests usually lay very small eggs in groups that normally are impossible to detect.

Life cycle: The rapid plant bug and tarnished plant bug: eggs - 10 days; nymphs - 15 to 20 days; number of life stages - five. Clouded plant bug: eggs - 12 to 14 days; nymphs - 10 to 18 days; number of life stages - five.

All plant bugs are multiple-host insects and spend most of the season on other hosts, which they prefer over cotton. Tarnished and rapid plant bugs overwinter as adults in ground trash near host plants. The clouded plant bug overwinters in the egg stage in the stems and stalks of host plants of various kinds. These pests are referred to as "true bugs" by entomologists because they do not pass through a larval or worm stage, and they do not go into the pupa or resting stage. When true bugs hatch, they resemble the adults except for size and often the absence of wings.

Critical timing of control measures: Treatment thresholds for tarnished plant bugs depend on stage of crop development and method of sampling. During the pre-bloom stage, thresholds may be adjusted downward if square retention drops below 80%.

Stage of Crop Treatment Threshold:

• Pre-squaring - 1 bug per 10 feet of row
  
• 1^st 2 weeks of squaring - 8 bugs/100 sweeps
  
• 3^rd week of squaring to bloom - 15 bugs/100 sweeps
  
• after first bloom - 15 bugs/100 plants or 3 bugs per 6 row feet
  

Yield losses and Prevalence: Tarnished plant bugs may be found in all Mississippi cotton fields. Prolonged heavy TPB infestations can result in substantial yi