Southern New Jersey (area south of Trenton)
Nearly all spinach, Spinacia oleracea L., is grown in the southern half of southern New Jersey.
The soils in this area are coastal plain, generally light soils ranging from sand to sandy loams, but areas of heavier, clay and silt loam soil do exist. Elevations are low with most of the area less than 200 feet in elevation. The warmest, seasonal temperatures occur in the extreme southern part of the state with the Salem County area being the warmest.
In New Jersey, spinach is a cool season crop that is raised in the spring, fall, and overwinter. Fields are planted as a series of beds, each comprised of several narrow-width rows to enhance machine harvesting. Planting dates of beds are staggered so that not all of the spinach in a field is ready for harvest at the same time.
The spring seeding typically occurs from March 12th to April 20th, placing harvest between May 20th and June 7th. This represents about 30% of the total acreage. The fall seeding typically occurs from August 10th to August 31st with harvest from September 25th to October 10th. This represents about 50% of the total crop acreage. The overwinter seeding typically occurs from October 1st to 15th, with harvest in the spring. This represents about 20% of the total crop acreage.
The method of harvest and relative size of fields planted depends upon how the crop will be marketed. For processing spinach, the leaves are clipped so that two harvests are made from the same planting. Fresh market plantings are harvested once, because the plants are cut and bunched for fresh market. As a result in the difference in marketing, processing fields range from 25 to 300 acres, whereas fresh market fields range from 1 to 10 acres. Usually farmers that raise processing spinach will not also raise fresh market spinach and the reverse is generally true.
Spring seeding Planting is recommended from March 12 to April 20 placing harvest between May 20 and June 7. This represents about 30% of the total acreage.
Fall seeding Planting is recommended from August 10 to August 31 with harvest from September 25 to October 10. This represents about 50% of the total crop acreage.
Overwinter seeding Planting is from October 1 to 15 with harvest in the spring. This represents about 20% of the total crop acreage.
Fall planting of processing spinach, Elmer, New Jersey.
Post-emergent pesticides would be applied by ground sprayers from tractors or terragators (large 3 wheeled tractors often equipped with boom sprayer arms) both with enclosed cabs. Thus, exposure to pesticides to applicators is minimal. Seabrook (processor) fieldmen visit fields about twice a week starting at plant emergence and make recommendations for pest control up until harvest. More distant fields may be visited once a week and there the field men have to confer with the grower before entering the field because the grower may have made a pesticide application on their own. Currently the longest REIs exist for methomyl and dimethoate at 48 hours; permethrin at 24 hours; and spinosad and tebufenizide at 4 hours; these REIs do not negatively impact the activities of field men. It is roughly estimated that REIs greater than 7 days would negatively inspection by field men.
Processing spinach is machine harvested so that there is little or no risk of pesticide residue exposure to the harvesters. Lengthy preharvest intervals exist for several of the organophosphate and carbamate pesticides: 7 days for methomyl, 14 days for dimethoate, 14 days for carbaryl, 14 days for thiodicarb and 21 days for mefenoxam and Ultra Flourish, fungicides. Depending upon the pests present near harvest, increasing days to harvest restrictions could become a problem since an insecticide application is always made just prior to harvest to ensure that there is no insect contamination in the harvested crop. So, preharvest intervals of greater than 7 days would negatively impact spinach harvest and overall crop production. If the pesticide's effectiveness extends as long as the pre-harvest interval then the phi is no longer a concern.
In New Jersey, the primary insect pests of spinach are: seed corn maggot, spinach flea beetle, aphids, leafminers, cabbage looper, beet armyworm, garden webworms, grasshoppers
Seed corn maggot – Seed corn maggot is a small fly that is attracted to rotting organic material and is a frequent pest of planted crop seeds, especially in cool, wet weather where seed germination is delayed. Eggs are laid at the soil surface where they hatch and the larvae (maggots) migrate to the food source. Destruction of seed and young seedlings can be severe requiring replanting of a crop. The most severe damage occurs in the spring particularly in fields that have had large amounts of plant matter incorporated during tilling. There are multiple generations a year.
Spinach Flea beetle – Flea beetles frequently attack leafy green vegetables. Eggs are laid on the soil surface and larvae feed on plant rootlets, seldom causing significant damage. The adults cause the shot-hole feeding damage in leaves, which sometimes becomes extensive. Usually, only the smaller seedling plants are at risk from flea beetles and the most severe damage occurs on field borders or at the edge of plantings. Depending upon the species of flea beetle there may be multiple generations each year.
Threshold.
Aphids – Aphids, usually green peach aphid, feed on the plant sap and may cause plant stunting if large numbers exist. Feeding damage results in curled leaves and stunted plants. Aphids may further transmit viral diseases such as spinach mosaic. In New Jersey, peak aphid populations occur in May and June, and again in mid-September through October. Since cooler weather generally favors aphid populations they may increase problems with insect contamination near harvest by drawing in predators and parasites that would normally feed on the aphids. Adult aphids overwinter on cultivated greens and weeds.
Threshold
Leafminers – These are small flies of two species, spinach leafminer and vegetable leafminer that attack the leaves. Eggs are laid in the leaf tissue where they hatch and the larvae begin to feed between the upper and lower leaf cuticle. As the larvae grow they produce a larger mine that snakes it way across the leaf. Mature larvae cut through the leaf cuticle and fall to the ground to pupate. Adult flies emerge from the soil and reproduce. There are multiple generations. Leafminers not only damage the leaf reducing photosynthesis but also contaminate the leaves. Generally these are minor pests but can be significant pests in some years.
Threshold
Cabbage looper – Like other caterpillars these insects feed on the foliage and should be considered one of the major pests of spinach. Damage occurs mostly in late summer and early fall. Cabbage loopers may be present at harvest and therefore be a contaminant as well as their feces.
Beet armyworm – This is a migratory pest from the southern states that is found from mid to late summer in several vegetable crops in New Jersey. The armyworm caterpillar is a foliage feeder capable of consuming large amounts of foliage. The fall planting of spinach is the most susceptible to beet armyworm. The moths lay their eggs in the hearts of the plants, with larvae feeding on the buds and terminal growth. Webbing may be produced on the leaf surface.
Until the advent of newer insecticides a few years ago, beet armyworm was a serious pest, but is now considered a minor pest.
Threshold
Garden Webworms - Moths begin laying eggs in fall planted spinach soon after plant emergence in mid-August. Larvae move into the growing point ("heart") of the plants, producing silk, often tying all of the "heart" leaves together. The caterpillars consume leaf tissue causing stunted plants and distorted plant growth.
Threshold
Grasshoppers – Several species occur in field borders and primarily a problem with processing spinach grown in the fall; do not cause feeding damage on the leaves, but they are a major contamination problem during harvest of fall spinach.
Petiole maggot – This is a newly observed, unidentified pest that is related to the seed corn maggot and root maggots. A single larva, maggot, is found per plant. The maggot feeds on the meristematic tissue and bores into the base of the petioles. Damaged plants are smaller and maturing leaves are contorted and misshapen. Up to 10% of the plants in the field were found infested. Found in the fall on 2000, it is unknown whether this fly attacks spinach in the spring and summer.
According to local spinach processors, any insect contamination in harvested plants is unwanted, regardless of whether the contaminating insect is a pest or beneficial. Insects such as lacewings and others that produce webbing (either at pupation or otherwise) are especially difficult because the webbing adheres to the foliage. Parasitized aphids also cause problems in that they adhere to the foliage and remain even after the parasite has left.
Insect Pests in New Jersey Spinach (4)
General Use Insecticides
Insecticides used in 2000 – last year of available dataRestricted Use Insecticides
Insecticides used in 2000 – last year of available data
Current (2002) Pesticide Recommendations for Insect Pests, Product Rates Per Acre and Use (G=general, R=restricted) (4)
Flea Beetle
Aphids
Leafminers
Grasshoppers
Garden Webworms
Processing spinach is largely sold to one processor and, while the individual farmer is responsible for maintaining the quality of the crop, the main emphasis is acceptable, marketable produce.
Chemical Use in Resistance ManagementProducers are always encouraged to rotate chemical classes of pesticides.
Alternatives
There is no current alternative to insecticide use.
Cultural Control Practices
Cultural controls focus largely on maintaining a well-fertilized, healthy crop. Since spinach is a cool season crop there is little latitude in planting dates being shifted to avoid pest problems. Harvest is completed as quickly as plants are ready.
A combination of the following cultural strategies can be used to reduce problems with seed corn maggot (4):
Biological Controls
No current intentional uses of biological control. Parasites have been recovered from the petiole maggot so that it appears that damage from this insect could be worse than is currently found.
Post Harvest Control Practices
Growers are encouraged to till under crop residues immediately after harvest. This enhances rapid breakdown of residues and mechanically induces mortality to remaining insect crop pests.
All weeds are pests in spinach, because they will compete with spinach for nutrients, water, and space. Generally, weeds are considered to be at threshold when they are distributed at the rate of 1 weed per square yard. Weeds have a zero tolerance threshold at harvest because of the extreme difficulty of separating weeds from spinach for processing. Weeds still cause problems for fresh market spinach because workers must separate the weeds by hand before bunching.
Summer Annuals
All annuals and especially zero tolerance weeds including nightshades, morningglory, jimson weed, common cocklebur, and chickweed.
Perennials
Zero tolerance weeds including Horsenettle, yellow nutsedge, Canada thistle, common milkweed, help dogbane, field bindweed, johnsongrass, bermudagrass, and quackgrass. These weeds especially should not be allowed to become established because of either intense competition with the crop or increasing difficulty of harvest.
Fall planted and Over-wintered crop
Winter Annuals
All winter annuals.
Summer Annuals
All summer annuals, and especially zero tolerance weeds including nightshades, morningglory, jimsonweed, and common cocklebur.
Perennials
Zero tolerance weeds including Horsenettle, yellow nutsedge, Canada thistle, common milkweed, help dogbane, field bindweed, johnsongrass, bermudagrass, and quackgrass. These weeds especially should not be allowed to become established, because of either intense competition with the crop or increasing difficulty of harvest.
Herbicides used in 2000 – last year of available data, NJ Pesticide Control Program General Use Herbicides
Chlorpropham –
Metolachlor –
Phenmediphan –
Sethoxydim –
Glyphosate –
Chemical Use in IPM Programs- None
Chemical Use in Resistance Management- Growers are urged to use different chemical classes for spraying for weeds.
Alternatives- Depending upon circumstances and the weeds involved, hand weeding may be done to make sure that the weeds are removed.
Cultural Control Practices- Crop rotation is recommended to assist in weed management.
Biological Controls - None
Post Harvest Control Practices- Tillage immediately after harvest is encouraged to reduce pest populations. After the spring crop, any weeds in the field when the spinach is harvested, especially for processing, would remain as a cut stem. By tilling the field the weeds would be destroyed before they have a chance to regrow and go to seed.
Downy mildew (blue mold) – Downy mildew is probably the most important spinach disease, being the most troublesome in cool, wet weather (temperatures of 2 to 25 degrees C), which are frequently the conditions experienced in New Jersey in fall, winter and spring. However the disease in New Jersey is relatively rare due to the use of the fungicide, Ridomil. Under ideal conditions the disease can spread rapidly and significant yield loss can result. Lesions occur primarily on the undersurface of leaves and when sporangia develop they have a bluish hue, giving rise to the name blue mold. There are several races of the disease, which makes it more difficult for selecting disease resistance varieties.
Threshold - Presence of the disease.
White rust – Another foliar disease, white rust appears as a small yellowish spot on the upper surface of the leaves. As these lesions develop, glassy white pustules form which eventually release spores. An entire leaf may become infected and die. Ideal conditions for disease spread are cool nights with heavy dew alternating with warm, dry, sunny days. This disease is the most troublesome for processing spinach in New Jersey being the most abundant in the spring and winter crops. Resistant varieties are available.
Threshold - Presence of the disease.
Anthracnose – Anthracnose is probably the major leaf spotting disease-afflicting spinach. Initial symptoms are small, water-soaked areas on both old and young leaves. These areas develop into yellow or necrotic lesions. The older lesions are tan and appear papery. Eventually lesions may coalesce causing the leaf to be wilted. Anthracnose is also a secondary infection often infecting leaves with other diseases, especially white rust. Wet conditions, dense plantings, poor air circulation, and low soil fertility favor the disease. Anthracnose is most troublesome in the fall plantings, especially with susceptible varieties, such as, Seven R. There are several other foliar diseases that will also reduce marketability but these are minor pests and are seldom sprayed for.
Threshold - Presence of the disease.
Root disease complex - Several diseases combine to create root problems, including pythium, rhizoctonia, Phytophthora, and fusarium. These soil-borne fungal pathogens typically persist in fields for years and infect susceptible plants when conditions are optimal. Crop rotation, planting fields with good drainage and using resistant varieties whenever possible are probably the best ways to manage these diseases.
Insecticides used in 2000 – last year of available data, NJ Pesticide Control Program
Azoxystrobin –
Copper –
Copper hydroxide –
Fosetyl-aluminum –
Mefenoxam –
Metalaxyl –
Current (2000) Pesticide Recommendations for Disease Pests, Product Rates Per Acre and Use (G=general, R=restricted) (4)
Damping Off
Downy mildew (Blue mold), white rust, leaf spots, anthracnose
Chemical Use in Resistance Management- Growers are urged to use different chemical classes for spraying for diseases.
Alternatives - There are resistant varieties available for downy mildew, depending upon the race of the fungus.Cultural Control Practices- None
Biological Controls- None
Post Harvest Control Practices - Farmers are encouraged to till under crop residues as soon as harvest is completed to help break disease cycles.