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University of Hawaii at Manoa



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Squash insects, pests, and plant disease pathogens, Knowledge Master, CTAHR
Ask the Experts--Squash



Summer squash can be grown successfully year round in Hawaii as warm weather is required for best growth and production. For minimum risk of crop failure caused by unfavorable weather conditions, it would be best to plant from late spring to the late summ er months.


Types of summer squash that most commonly grow in Hawaii are Zucchini, Summer Crookneck, Early Straightneck, White Scallop, and Cocozelle. Any of the varieties or hybrids listed for each type will grow well in Hawaii.


Weed Management

Weed whenever necessary when the plants are small; weeding will become more difficult as the squash plant grows into a bush. Squashes have a shallow root system, so shallow cultivation is necessary to avoid injury to the root system. Irrigation frequency is largely dependent upon soil type and weather conditions. Lighter soils require more frequent irrigation than heavier soils. As the plants begin to set fruit, more frequent irrigation becomes necessary.


Diseases most commonly affecting squash production are damping-off, nematodes, powdery mildew, and mosaic viruses. Damping-off and nematodes can be controlled by the use of captan-terrachlor soil treatment for damping-off and by using nematicide fumigation for nematodes, or by planting in clean soil.

Powdery mildew can be controlled by the use of maneb, zineb, or copper fungicides. Watermelon mosaic virus, squash mosaic virus, and cucumber mosaic virus may be problems in squash production. There is no control, so infected plants should be destroyed. Best preventatives are insect control and clean cultivation, as certain weeds are hosts to these viruses.



Squashes can be grown on a wide variety of soil types but will do best on a medium-textured soil. Good yields can be produced on lighter and heavier soils if they are properly managed. Basic requirements are that the soil be well drained and well supplied with organic matter. Squashes grow best at a soil pH of 6.0 to 7.0. Manure or compost at the rate of 10 to 20 pounds per 100 square feet will improve the soil condition and fertility. Drainage can be improved by working the soil to break up any hardpan. The compost and manure should be worked into the soil to a depth of 6 to 8 inches. If nematodes are present, fumigate after soil preparation and allow 2 to 3 weeks before planting.

Nutrient needs

A general garden fertilizer such as 10-30-10 can be used at the rate of 2 to 3 pounds per 100 square feet. One-half of the fertilizer is applied at planting in a single band placed 2 to 3 inches to one side and below the seed. The remaining half of the fe rtilizer can be applied 4 weeks later. Additional nitrogen may be applied at the beginning of harvest to prolong plant vigor and fruit production.


Summer squashes usually produce fruit ready for harvest 50 to 60 days after planting. Fruit should be picked at an immature stage when the flesh and skin are tender and succulent. The squash fruit grows rapidly, so daily or every other day harvest is nece ssary. The length of harvest will depend on plant vigor and freedom from disease.


Insects that commonly attack squashes are the aphid, cutworm, leaf miner, melon fly, and white fly. Some measure of control is necessary to ensure a successful crop. A general purpose spray, available under various trade names at garden shops, can be used according to directions on the label. The best insect control practice is the use of a regular spray schedule to prevent build-up of insects. Diazinon, malathion, or naled (Dibrom) can control most of these insects.

The melon fly is probably the most destructive insect of the squash. The adult female oviposits eggs in the stem and young fruits. The developing larvae feed on the surrounding plant tissue and may kill the plant and destroy the fruit. The use of regular spray programs and bagging of young fruit with brown Kraft bags soon after pollination may help control melon fly damage. Squashes are dependent upon bees for pollination. As insecticides are toxic to honey bees, spraying or dusting should be done in the late afternoon when flowers are not fresh and the bees are less active.


Summer squash are planted at the rate of 2 ounces of seed per 100 feet of row . As summer squashes produce fairly large bushes,spacing between rows and between plants is important. Distance between rows should be from 3 to 4 feet, and distance between pla nts within the row should be from 24 to 30 inches. Plant seeds directly into the seedbed at a depth of 1/2 to 1 inch.