General Production Information
 

Production figures (1) for fresh market squash in Delaware are combined with those of other vegetables (asparagus, beets, lima beans, broccoli, cauliflower, green peas, greens, hot and sweet peppers, sweet potatoes, and turnips) to avoid disclosure of individual operations.
 

• •Acres of "Other Vegetables" planted in Delaware increased from 700 in 1997 to 800 in 1999.
• •Acres harvested increased from 680 in 1997 to 740 in 1999.
• •Production increased from 24,000 Cwt. in 1997 to 26,000 Cwt. in 1999.
• •Value increased from $989,000 in 1997 to $1,787,000 in 1999.

 

• •Acres of "Other Vegetables" planted in Delaware decreased from 9,850 in 1996 to 8,870 in 1999.
• •Acres harvested decreased from 9,850 in 1997 to 8,219 in 1999.
• •Production decreased from 38,890 Cwt. in 1997 to 35,474 Cwt. in 1999.
• •Value decreased from $6,118,000 in 1997 to $5,925,000 in 1999.

 

Squash can be grown throughout Delaware.
 

Cultural Practices (3)

Summer squash is harvested and eaten in the immature stages when the rind is still very soft. Grown on bush-type plants, most summer squash will mature in 45 to 60 days, yielding about 8 to 12 pounds per plant. Many excellent varieties are available:
 

Straightneck types - Early Prolific, Straightneck, Seneca Prolific

Crookneck types - Golden Summer, Crookneck, Sundance

Zucchini types - Black Magic, Aristocrat, Elini

Scallop types - Patty Pan Hybrid, Peter Pan
 

Winter squash is harvested when the fruit is mature and the rind is hard, which can be 70 to 110 days after planting, depending on variety. Winter squash usually grow on vines, but some are of the bush type. Included in the winter squash category are: hubbards, butternut, gold nugget, acorn, and buttercup. Expected yield for the vine

types is about 30 pounds per hill, and for bush types about 5 pounds per hill. Some of the most popular varieties in this category are:
 

Hubbards - Blue Hubbard, Improved Green Hubbard

Butternut - Early Butternut, Waltham Butternut

Gold Nugget - Gold Nugget

Acorn - Jersey Golden Acorn, Table King, Table Queen, Table Ace, Royal Acorn

Buttercup - Sweet Mama, Buttercup
 

Squash do well in most well-drained soils, high in organic matter and with a pH of 6.0 to 6.8. Before planting, broadcast 5 pounds of a complete fertilizer such as 5-10-10 or 5-10-5 per 100 sq. feet If manure is used, broadcast 2 to 4 bushels plus about 3 pounds of a complete fertilizer per 100 sq. feet After spreading the fertilizer and lime, rototil or spade the soil to a depth of 6 to 8 inches to develop a good seed bed. Squash can be started by planting seeds after danger of frost is over. Plant three seeds

per hill and later thin to the best one or two plants per hill. Plant bush type summer squash in rows 5 to 6 feet apart and space the hills about 3 feet apart within the row. For vine types of winter squash, plant seeds in rows 6 to 12 feet apart and space hills 3 to 10 feet apart, depending on variety. When summer squash begins to bear or when vine types begin to run, apply fertilizer around each plant, being cautious to keep the fertilizer at least 2 to 3 inches from the stems of the plants.
 

Insect Pests in Delaware

The major insect pests of both processing and fresh market squash are striped and spotted cucumber beetles and melon aphids. Although only a pest of concentrated squash acreage, squash vine borer can also cause economic losses.

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Striped and spotted cucumber beetles

Damage and Life Cycle:Striped cucumber beetles, Acalymma vittata (Fabricius), and spotted cucumber beetles, Diabrotica undecimpunetata howardi (Barber), are the most destructive insect pests of cucumbers, squash and related crops in the mid-Atlantic area. Both cucumber beetles share a similar life cycle and inflict similar damage to host plants. Both species overwinter as adults in neighboring woodlands or other protected areas and move onto crops in May, just after plant emergence or transplanting . Beetle feeding on the young seedlings often kills the plants within 1 to 2 days. Female cucumber beetles deposit eggs in the soil at the base of host plants or on the underside of leaves. Larvae feed on the roots of the plants for 2 to 3 weeks before they pupate in the soil. A second generation of beetles appears later in the summer. Squash are particularly susceptible to cucumber beetle damage, since planting dates often coincide with high levels of beetle activity. Cucumber beetles feed on the stems, foliage, and fruit, and can cause direct damage to the rind of winter squash . 

More importantly, both species of cucumber beetles are vectors of bacterial wilt, a serious disease in cucurbits . Bacterial wilt is a major consideration in the production of squash grown for processing and the fresh market . There is a variable level of resistance to bacterial wilt among squash cultivars, but when cucumber beetle populations are high even the more resistant varieties will show signs of stress that translate into a reduction in fruit quality and yield . Beetle emergence is well synchronized, and a field with few beetles may become densely infested literally overnight. Cucumber beetles are very active dispersers and can quickly locate host plants . For this reason crop rotations to control for cucumber beetles are of limited value, particularly on smaller farms . The major feeding injury and disease transmission takes place from the time cucurbits are transplanted or emerging through the surface until they form runners . Older plants are far less susceptible to disease transmission. Some evidence indicates that cucumber beetle may also transmit certain plant viruses, but this has not been proven . 
 

Frequency of Occurrence:Cucumber beetles are regular annual pests of both fresh market and processing squash. Although their feeding injury does not always result in economic loss, their control is critical to protect the crop from bacterial wilt. Beetle size and timing of cucumber beetle populations can vary widely depending upon weather conditions in winter and in late spring when beetles emerge.These variations in beetle populations have little effect on management practices of squash treated with preventive soil applications of carbofuran (Furadan), but prescribed foliar treatments vary with year to year or field to field fluctuations in beetle population density . 
 

IPM Program:A very small percentage of fresh market growers actively scout for cucumber beetles, since preventive insecticides are usually used . All squash grown for processing is scouted for pest problems, but the use of foliar rescue treatments alone is not a viable control strategy for cucumber beetles. Beetles often have irregular distribution in the field, and localized populations can be overlooked while scouting. The resulting yield loss due to bacterial wilt infected plants can be significant. Preventive insecticide treatments are used on all processing squash to control beetles during the early growth stage when squash plants are most susceptible to bacterial wilt transmission.
 

Chemical Controls:

Fresh Market Squash; The most common control strategy for cucumber beetles and bacterial wilt in fresh market squash is the preventive use of carbofuran (Furadan 3.8 fl oz 4F/1,000 ft of row at planting - a Special Local-Needs Label 24(c) in effect in Delaware). Admire labeled at the end of the 1999 season can now be used in addition to carbofuran. This strategy is used on 20 % of the acreage. Carbofuran treatment is generally effective for up to 4 weeks, but fields are scouted to determine the effectiveness of control . In some cases, foliar insecticides may be applied instead of, or in addition to, carbofuran treatment. If used in place of carbofuran, foliar insecticides are applied before beetles feed extensively on the cotyledons and first true leaves. Spraying begins at emergence (or after transplanting) and continues as long as beetles continue to invade the field. For the more resistant cultivars, foliar applications are applied only if beetles severely affect stand establishment during the cotyledon stage. For winter squash, adult beetle control is less important for the prevention of bacterial wilt because these crops are more tolerant to the disease. However, cucumber beetle feeding may cause direct damage to the rind and beetles may be controlled for this reason. In a typical year 1 to 2 applications of foliar insecticides are used on about 50% of fresh market acres planted for cucumber beetle control. During periods of heavy infestation, 3 sprays may be needed; if infestations are light, fields may not be treated with foliar insecticides. Endosulfan (Thiodan 2 pt 3EC/A) is the most popular foliar insecticide used ( used on 30% acreage, because it is effective against cucumber beetles and is not toxic to bee populations). Carbaryl (Sevin l.25 lb 80S/A) is used to a lesser extent ( 5% of the acreage), in part due to its high toxicity to bees. Where it is used, it is applied at night to minimize the impact on bee populations. Methoxychlor (2.5 lb 50WP/A), esfenvalerate (Asana XL 7.7 fl oz 0.66EC/A) and methomyl (Lannate) are used to a lesser extent ( less than 5% acreage treated with the previous insecticides). Processing Squash: Preventive applications of carbofuran ( a Special Local-Needs Label 24(c) in effect in Delaware for the use at 3.8 fl oz 4F/1,000 ft of row at planting) are used on 95% of the processing squash grown in Delaware to control the spread of bacterial wilt. Admire labeled at the end of the 1999 season can now be used in addition to carbofuran.These products are very important to growers to control cucumber beetles during the young stage when plants are most susceptible to bacterial wilt transmission. Growers scout for beetles during this vulnerable seedling stage and will apply foliar products if beetle populations are high. In addition, foliar insecticides are sometimes applied during the production season to limit feeding damage of beetles. The most popular choice is endosulfan (Thiodan 2 Pt 3EC/A) being used on 80% of the acreage. Carbaryl (Sevin l.25 lb 80S/A) is the second choice, although toxicity to bees (required for pollination) is a concern. Esfenvalerate (Asana 5.8-9.6 fl oz 0.66EC/A) and methomyl (Lannate 1.5-3 pt LV/A) are also used on less than 5% of acres during the growing season. Processing squash is harvested on a 48 hour schedule, so insecticides with a days-to-harvest interval exceeding 2 days (such as esfenvalerate and methomyl) are avoided near harvest time. These insecticides are rarely used by themselves, but are included in tank mixes with fungicides and are applied aerially. 
 

Alternative Controls:No alternative strategies are available for controlling cucumber beetle on squash in Delaware. 

Melon Aphids 

Damage and Life Cycle:Many species of aphids feed on squash; however, the predominant species is the melon aphid. All inflict similar types of injury to plants. Aphids overwinter as eggs on a variety of host plants. Nymphs hatch in spring and feed until they mature. Adults of this first generation reproduce sexually, bearing live young which become winged adults which migrate to crops. This generation feeds on plants and rapidly reproduces asexually, with a generation time of 5 to 7 days. Melon aphids are found primarily on the underside of the leaves, where they suck sap from the plant and cause a reduction in the quality and quantity of the fruit . Infested leaves curl downward and may turn brown and die. In addition to feeding damage, aphids produce "honeydew," a sticky excretion which can cover fruits and promote the growth of a sooty black mold . More importantly, the melon aphid is also one of the primary vectors of cucumber mosaic virus, which may reduce yields as much as 50-80% in plants infected prior to fruit set . 
 

Frequency of Occurrence:Aphids are rarely a problem on fresh market squash, and are generally controlled by insecticides applied for major pests . However, populations occasionally reach damaging levels . Aphids are more problematic on winter squash than summer squash because of the longer growing season . The worst infestations usually occur during hot, dry summers following cool, dry springs, since such weather conditions reduce the efficiency of aphid natural enemies . Chemical applications which deplete populations of beneficial insects may also lead to aphid outbreaks.

IPM Program:Scouting for aphids is done by looking for wilting and curled leaves throughout the field. When aphids are detected, more intense sampling is done to determine infestation levels and natural enemy activity. An insecticide is applied if more than 20% of runners have 5 or more aphids, natural enemy populations are low, and humidity is low to moderate. 

Chemical Controls: Admire used at planting for cucumber beetle control will also provide control of early season melon aphid populations. Methomyl (Lannate 2.25 pt LV/A) is the only foliar product that offers sufficient control of melon aphid in summer squash is the most commonly used on 5% of the acreage. However, methomyl is not labeled for use against aphids in winter squash. Endosulfan (Thiodan 1.33-2.67 pt 3 EC/A) is the most commonly used product in winter squash and is also used by some processors on summer squash (10% of the acreage). Regardless of the foliar insecticide used, thorough spray coverage on the underside of leaves is important . In a typical year, one application to about 10% of fresh market and processing acres is required specifically for aphid control varying from zero to two applications, depending on aphid population levels during that year . In processing squash, aphid populations may be kept low by applications made to control other insect pests, particularly cucumber beetles. An insecticide may be tank mixed with a scheduled fungicide application if aphid or other pest insect populations are high. In addition to those chemicals listed above, diazinon (1 pt 4EC/A) and oxamyl (Vydate L 2-4 pt 2L/A) are labeled but are not generally used for aphid control in winter squash produced for the fresh market . Most growers practice good weed control since many weeds are alternative hosts for aphids.
 

Alternative Controls:

Natural Enemies:When making a treatment decision, natural enemy populations are considered. Aphids may be controlled by parasitic wasps and a variety of predators, including lady beetles and their larvae, lacewing larvae, and syrphid fly larvae . All of the insecticides used in squash are detrimental to beneficial insects. During periods of high humidity, fungal diseases may also help reduce aphid populations. Natural enemies are important to a certain extent but do not always keep pest populations in check. 
 

Cultural Controls:Foil mulches on squash planted after July 1 may repel aphids that transmit mosaic virus. A few small fresh market growers may use this strategy on late planted squash, but it is rare.

Minor Insect and Mite Pests in Delaware

Most of the minor pests listed in this section do not cause economic damage every year. Typically, they are adequately controlled by insecticide applications directed against cucumber beetles and aphids. Summer squash is very short-lived and thus rarely experiences significant problems with minor pests; whereas, winter squash has a long crop season and is more vulnerable to these late developing pests. 
 

Spider mites

Damage and Life Cycle:Spider mites can be a serious problem on squash during hot, dry weather. Adults migrate into fields in the summer and begin feeding on the underside of leaves. Each female can lay 5 to 6 eggs per day for a total of 70 to 200 eggs in her lifetime. Eggs hatch into 6-legged nymphs which quickly develop into adult mites. The life cycle can be completed in as few as 6 days during hot weather. These minute mites feed on the contents of individual cells of the leaves, which become blotched with pale yellow and reddish-brown spots ranging from small specks to large areas on the tops of leaves. Damage can develop very quickly, and a severe infestation can seriously stunt the growth of plants. 
 

Frequency of occurrence:Mites are a sporadic pest problem in squash and are more problematic on winter squash than summer squash because of the longer growing season . Outbreaks are typically more severe during hot and dry weather or when insecticide applications, particularly of carbofuran, reduce natural predator populations. 
 

IPM Program:Because of their small size, spider mites are hard to detect until the vines are damaged with hundreds of mites on each leaf. The problem with scouting for mites is that populations may be spotty and easily missed even by a thorough scout. Fields are scouted by some growers weekly, from early July through August during hot, dry weather . Mites may be concentrated around field edges during the early stages of infestation, or they may balloon into the center of the fields and spread from there. If feeding injury is detected, plants are sampled to determine the extent of mite infestation. An acaricide is applied if 10-15% of the crown leaves are infested early in the season, or in mid-summer if 50% of the runners show leaf injury and mites are present . 
 

Chemical Controls:Most fresh market growers seldom treat for spider mites. When infestation levels are low, chemical control of mites is unnecessary. During the worst infestations, two sprays may be used on about 30% of the acres. Even when mite populations are high, infestations tend to be localized and may be spot-treated . Applications to control mites on processing squash are not needed every year. Typically, less than 13% of processing squash acres are treated every 2 or 3 years for spider mites. Spider mite outbreaks may occur about once every 5 years. In the worst cases, up to 50% of acres are treated.

The most frequently used chemical control in Delaware on both fresh and processing squash is dicofol (Kelthane 1.25 lb 50WP/A) (2, 5). Abamectin (Agri-Mek 8-16 fl oz 0. l5EC/A) is expensive but effective, and is being used with increasing frequency to control the worst spider mite populations in fresh market squash (less than 2% of the acreage treated). Abamectin is not used during harvest because of its long (7-day) days-to-harvest interval (2). Regardless of product choice, proper application techniques are essential for effective mite control. The use of surfactants and the proper spray equipment is essential to ensure that the product reaches the underside of the leaves.

Alternative Controls: None
 

Squash Bug (Anasa tristis) Damage and Life Cycle:The squash bug attacks all the cultivated plants of the cucurbit family but favors squash and pumpkins. Both adults and nymphs feed on the leaves by piercing through the surface with their sharp mouthparts and sucking the plant sap. In the process of feeding, they inject toxins which interfere with the physiological functions of the leaf. The first evidence of injury is the formation of pale green areas on the leaves. These areas later wilt, turn brown and die. When squash bugs are abundant, the foliage has a somewhat burnt appearance

.

Frequency of Occurrence:The squash bug is an important pest in home gardens but is only an occasional pest in commercially grown fresh market squash and is never a pest on squash grown for processing . It is more problematic on winter squash than summer squash because of the longer growing season. 
 

IPM Program:Squash bug control is not considered in IPM programs in Delaware.
 

Chemical Controls:Less than 5% of fresh market squash is treated for this pest . Treatments begin shortly after vines run and are repeated every 7 to 10 days or as needed. Chemicals used for squash bug control in fresh market squash include :

permethrin (12.8 fl oz Ambush 2EC/A or 8 fl oz Pounce 3.2EC/A) [winter squash only]

esfenvalerate (Asana XL 5.8-9.6 fl oz 0.66EC/A)

carbaryl (Sevin l.25 lb 80S/A)

Processing squash is never treated specifically for squash bug . 

Alternative Controls:There are no alternative control strategies for squash bug in squash in Delaware.
 

Squash Vine Borer (Elasmopalpus lignosellus)

Damage and Life Cycle:Squash vine borers are pests of squash and pumpkins, particularly in the home garden . Moths overwinter as pupae in the soil . After emergence, the wasp-like moth can be seen flying swiftly and noisily about plants during the daytime from June through August . Eggs are laid singly at the base of blooming plants and hatch in 7 to 10 days . Small larvae usually are found tunneling out the inner tissues of petioles near the base of the plant, where they feed for 14 to 30 days . Later in the season, older larvae are located throughout the stems and sometimes in the fruit. The first indication that the borer is present is the sudden wilting of one runner or the entire plant. Inspection of the wilted vine usually reveals masses of coarse greenish-yellow excrement pushed out of holes in the vines. Infested vines often are completely girdled and usually rot and die.
 

Frequency of Occurrence:The squash vine borer is a rare, sporadic pest of fresh market and processing squash in Delaware. Commercial plantings usually escape noticeable injury in the mid-Atlantic area. However, in areas where squash is planted every year, we have seen an increase in problems.
 

IPM Program:There are no practical methods for direct sampling of adults or eggs in the fields. Pheromone traps used for clear-wing moths have been used to get a general indication that moths are flying and laying eggs. Plants are checked for general vigor and other factors, and borer damage may be detected, but no regular monitoring is done specifically for this pest in either fresh market or processing squash. 
 

Chemical Controls:Less than 5% of fresh market and processing acreage is treated for squash vine borer. Esfenvalerate (Asana XL 5.8-9.6 fl oz 0.66EC/A) and endosulfan (Thiodan l.33-2.67 Pt 3EC/A) are the preferred products. A single application may be used in years when infestation levels are high 
 

Alternative Controls:In small plots, infested runners may be removed or infested plants destroyed, but no cultural or alternative practices are used by commercial growers. 
 

Weeds

Annual and Perennial Broadleaves and Grasses
 

Frequency of Occurrence: Annually.
 

Damage Caused: Reduced yields from weed competition, loss due to hindrance with harvesting equipment, and harboring damaging insects and diseases. Crops can become contaminated with weed plant parts (e.g. nightshade berries, Canada thistle buds or daisy buds) during harvesting which can result in reduced selling price or in severe cases, rejection of the crop.
 

% Acres Affected: 100%
 

Pest Life Cycles: A wide range of summer and winter annual and perennial weed species is present in squash fields in DE. Some of the more common weeds include common lambsquarters, pigweed species, common ragweed, morningglory species, and various annual and perennial grasses.
 

Timing of Control: Preplant, at planting, and postemergence.
 

Yield Losses: Can be as high as 100% in severely infested fields
 

Regional Differences: While weed species spectra can vary regionally, they are a serious squash pest throughout the Delaware.
 

Cultural Control Practices: Herbicides alone seldom control all weed species. They must be used in conjunction with cultivation to ensure high yields in squash crops. When weed escapes occur, cultivation is preferable to hoeing or applying post-emergence herbicides. Hoeing is more expensive and labor intensive than cultivation, and post-emergent herbicides may injure the crop and cause a delay in harvest. Also, since post-emergent herbicides are selective, it is unlikely that all weed escapes will be controlled.
 

Biological Control Practices: None.
 

Post-Harvest Control Practices: Application of herbicides and/or tillage after harvest can control weeds.
 

Other Issues: Research on squash weed control is ongoing.

Chemical Controls:
 

Use in IPM Programs: Use of these herbicides is consistent with IPM recommendations. Postemergence herbicides (sethoxydim and paraquat with squash growth with plastic) support the use of scouting and as-needed applications.
 

Use in Resistance Management: None reported.
 

Efficacy Issues: The listed herbicides have different but overlapping spectra of species control. Bensulide and clomazone re effective on annual grasses and some broadleaf weeds. Ethalfluralin is effective on annual grasses. Emerged grasses are controlled with sethoxydim. Producers have a great need for new herbicide registrations, especially for herbicides, which will help control problem perennial weeds such as Canada thistle or yellow nutsedge.
 

Alternatives: Limited number of herbicides is currently being tested.
 

Contacts:

Subject matter contacts at the University of Delaware, College of Agriculture and Natural Resources:

Joanne Whalen 

Bob Mulrooney 

Mark Van Gessel 

Ed Kee 

TracyWootten
 

References:

(1) Delaware Agricultural Statistics Summary. Vegetables for Fresh Market, Delaware 1997 - 1999. http://www.nass.usda.gov/de/p17.htm
 

(2) Delaware Agricultural Statistics Summary. Vegetables for Processing, Delaware 1970 - 1999. http://www.nass.usda.gov/de/p18.htm
 

(3) Kee, Ed. 1996. Squash and Pumpkins. University of Delaware Cooperative Extension. HG - 29. http://bluehen.ags.udel.edu/deces/hg/hg-29.htm
 

Authors:

Joanne Whalen - INSECTS 

Mark VanGessel - WEEDS 

Susan Whitney - General Information