Squashing the Problem: Issues to Look Out for on Your Late-Season Cucurbits

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It has been a tough time in the vegetable garden in 2022. Between the weatherman and the insects, getting any produce out of your garden is nothing short of a labor of love. Isn’t it all worth it when you eat that first fried squash or go pumpkin patch hopping? There are some common pests and diseases keen gardeners need to be on the lookout for to make sure their Crooknecks, Burpless Cukes, Black Beauties, and Jack o’Lanterns survive to produce fruit.

What are ‘Cucurbits’?

Cucurbits refer to any plant in the plant family Cucurbitaceae. Gardeners and farmers know them more as squash, cucumbers, melons and pumpkins. One of the things that makes them related is their similar flower structure (compare them sometime!). Knowing these vegetables are related can help gardeners and farmers more efficiently manage insect and disease issues, as there are a lot of shared issues among the family members.

Main Problems

Weather– Not just humans and their animals suffer when it is hot and dry outside! Plants get stressed by adverse weather and temperatures, and this stress causes them to become more susceptible to pests and diseases. Make sure when there are long periods of hot, dry weather to do your best to apply supplemental water to your plants, and consider keeping the soil mulched with organic material (e.g. pine straw, wood chips, compost, etc.) to conserve soil moisture.

Squash Bugs (Anasa ssp.)- In Eastern North Carolina, be on the lookout for at least two generations of these true bugs in May and August. These small insects are voracious feeders and will suck the juices right out of the plants. The adults survive over the winter and lay their small, shiny, brown eggs usually on the underside of Squash bugsquash leaves (sometimes in melons and rarely in cucumbers) in organized clusters. Be on the lookout for the adults, because if you see them then they are surely laying eggs! If the adults aren’t seen, still look at the leaves in May and August to catch the insects at their egg stage. The easiest thing to do to stop them is to smoosh the eggs or small insects before they get big. There are other chemical options if the infestation is extensive or there are more than a handful of plants. Call theN.C. Cooperative Extension – Lee County Center for more chemical information (919-775-5624).

Squash Vine Borers (Melittia cucurbitae)- Most home gardeners don’t know they have these sneaky caterpillars until they notice their plants suddenly start wilting. They might not realize the beautiful moth they saw flying through their garden is the culprit though. The caterpillar of the one of our clearwing moths eats its way inside the stem of the squash and uses the plant for food and protection from the outside. If the squash plants suddenly wilt, even though they have been recently watered, check the stem for wet, spongy material coming from a wound. Sometimes using a wire or cutting a slit parallel to the stem can access the caterpillar so it can be killed. Just rebury the stem under mulch and compost afterward, and water deeply. An early-season dose of bifenthrin or spinosad at the base of the plant can also stop the moth from laying her eggs at the base of the plant. Timing is everything!

Powdery Mildew– When plants look ‘ugly’ gardeners are usually the first to notice. The fungal pathogen called ‘powdery mildew’ looks like someone sprinkled white powder all over the cucurbit’s leaves. This is not necessarily going to kill the plant, but it will make it less efficient and weaken it. Usually plants that are growing in shady conditions with poor airflow through the garden are susceptible, as are plants where the weather has been hot, humid and wet. Variety selection and proper planting site will help mitigate the likelihood of an outbreak. There are many foliar fungicide spray options, as well. Call the N.C. Cooperative Extension – Lee County Center for more chemical information (919-775-5624).

Anthracnose– Many fungal pathogens like to affect the leaves of cucurbits, but one of the most common is Anthracnose (Colletotrichum orbiculare). Though not necessarily a problem when it is dry, this pathogen becomes an issue as the weather cools and rains return. The infection starts as brown spots where under water splashes on the leaves, but soon grows into larger, irregular papery spots. This affects every part of the plant, including the fruit, so diligent scouting is a must. Call theN.C. Cooperative Extension – Lee County Center for more chemical information (919-775-5624).

Fall sowing

Yep, last chance to plant your late-season squash seeds! Here’s more resources on what else to plant this time of year.

More Resources:

Amanda Wilkins is the Horticulture Agent with North Carolina Cooperative Extension in Lee County.