Answer: There are a number of tenacious pests/diseases that attack vining crops, and I'll provide info below. Good cultural practices can also help alleviate problems. Clean up and destroy (don't put in the compost pile) any diseased plants at the end of the year. Rotate crops each year so that plant specific pests and diseases have less opportunity to build up in the soil. Plant disease resistant varieties. Research shows that pests actually seek out stressed plants so build a good, healthy soil, and make sure your vining crops aren't stressed for water. Strong, healthy plants are your best defense.
The squash vine borer affects vining crops, in particular squash and pumpkin. Adult moths lay eggs on stems near the plant base. After the eggs hatch, white caterpillars with brown heads tunnel into the stems to eat. They cause vines to wilt, even though they are well-watered, and eventually the plant will die. Look for entry holes and sawdust-like droppings at the base of the plants. Slit the stem lengthwise from the hole toward the tip of the vine and remove the caterpillar. Cover the stem with soil and it will reroot. To prevent them, in early summer, cover the plants with a floating row cover until flowers appear, which helps stop the moths from laying eggs.
Bacterial wilt is a disease found mainly on cucumbers and muskmelons. A sign is when well-watered plants wilt during the day, but recover at night, and then eventually wilt and die. If you cut open a vine, the sap will be sticky and white.
Squash bugs are about 1/2" long, brown or grey, and shaped a bit like a shield. They suck the juices out of leaves and stems. They feed in groups. To control them, find their masses of reddish-brown eggs on the underside of leaves and squash them. Rotate crops every planting season and clean up plant debris, where the bugs can overwinter.
The spotted cucumber beetle (1/4 inch long, yellow w/black stripes or spots) is a common and voracious pest of the squash, melon and cuke family of crops. They not only eat plants, they can transmit diseases among them. Your first line of defense is to cover the seedlings with floating row cover while they're small and young - when they're most succeptible to damage and disease. When the plants outgrow the cover, if the adults beetles are a problem, you can use a botanical spray such as pyrethrin. I've also heard of organic gardeners who had luck using oil of clove as a repellent. Dab a couple drops on cotton balls and place them throughout the plot, and the beetles stay away. I hope this info helps!
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