Sunday, June 17, 2018
Home and Garden

Squash those stem borers

Stem borers that affect squash can be controlled

Q: I have a medium to large backyard garden in the Riverview area. Over the past three years, I have successfully grown potatoes, sweet potatoes, green beans, okra, peanuts, tomatoes, peppers, radishes, carrots, gourds, luffas, kolabra, watermelons, cantaloupe, onions, cucumbers, strawberries, etc.

My problem is squash. I get large beautiful plants, loaded with blooms, and then squash. Then it ends. The stem borers move in and take over. They bore into the young squash, the vines and destroy the plants and fruit.

I have tried seven dust and spray, mulch, neem oil, fish oil, organacide, picking and disposing of the young affected squash. I have tried it all early and often before I see any signs at all, but they always get me.

I live less than 2 miles from a farm that grew about 200 acres of squash with what seemed to be no problems. I have four 12- by 4-foot above-ground boxes, a 15- by 40-foot tilled up area, and another 20- by 20-foot tilled area. I rotate crops every six months. I use drip and mister irrigation. I fertilize and compost regularly. Robert Haymes, Lithia

Dr. Hort: The squash vine borer hatches from an egg, bores into the vine and begins feeding and growing in the hollow pith inside the stem, which in time will destroy the vine.

The larva is a white wrinkly grublike caterpillar with a brown head capsule grows to about 1 inch long in its largest form. The adult colorful moth looks like a wasp, 1/2- to 5/8-inch in length with an orange abdomen with black dots and greenish fluorescent wings.

The pupae is 5/8-inch long, brown in color, wrapped in earthen black silk found in the top 2 inches of soil.

There are many approaches to control borers, used singly or in conjunction with others. Above all, be ready before they arrive. To begin, place yellow sticky cards in and around your squash plants to monitor their arrival and begin spraying the plants and vines weekly with neem oil, following label directions.

The purest 100 percent neem oil that I've found is NimBioSys available online at This product comes from a grower of neem trees in the Tampa Bay area and their product still contains azadirachtin, a natural growth regulator, blocking molting into an adult, reducing the population and acting as a deterrent, which is missing in 70 percent neem oil products. It will also control powdery mildew, a common fungus problem on squash.

If you see a sawdust (worm poop) pile by a stem, slit it open, remove the worm and bury the section of vine with some soil. Another proactive approach on vining squash is to bury nodes (part of the vine where leaves are attached) every few feet to encourage rooting. If a borer gets in, only a small section will die, not the entire plant.

Lastly, rake the squash bed or vigorously till, then look for and destroy any pupae that got past your firewalls throughout your crop season.

And the reason why your 200-acre squash grower down the road doesn't have a problem is that he or she has an arsenal of professional-use insecticides at their disposal such as Thiodan, Ambush and Pounce. They also have the advantage of acres of squash, so they can lose a few plants. Having 200 acres of squash down the road is probably the reason you have such a problem, the ones that get away from the farm come to pay you a visit, so be vigilant and give 100-percent neem a chance.

Haymes: I tried triple-action neem oil but I will definitely try NimBioSys!

After I sent you my question, the "pests" were getting worse. I do have squash vine borers, but I think my bigger problem might be pickleworms. They moved from the squash to my cucumbers and then my melons.

I bought some BT spray because I have about 15 half-grown watermelons that I don't want to lose. Also, the worms are tiny and green in color.

Dr. Hort: The 100 percent neem oil works for pickleworm, also. The BT will work on small caterpillars.

Other biologicals to keep in your arsenal are products containing spinosad such as Conserve. It lasts up to a week and also kills upon contact. The only down side is that it's hard on bees, so spray evenings after bees have done their duty and gone home.