Squash Vine Borer
It’s not the “heartbreak of psoriasis” but it’s close…..the heartbreak of squash vine borers. You may have a huge zucchini or squash plant. Maybe in June you have already harvested a few crooknecks from the vine. All of a sudden one morning the entire plant is wilted to the ground. At the base of the vine, the stem is completely hollow and rotten. The squash vine borer has struck again!
In mid-May, an inconspicuous, clear winged moth laid an egg on the lower stem of your squash plant. The egg hatched and became a tiny grub, which immediately began boring into the green stem. When it reached the center, the grub began feeding and growing, unbeknownst to you. Finally, the damage to the stem became so great that the plant was cut off from its roots. With the death of the plant, the grub pupates in the soil, perhaps to develop into another adult moth, ready to damage your garden again.
There is little to be done after the vine wilts. The vine will not survive the stem damage, it just becomes good compost. Next year, resolve to plant squash and cucumbers as early as the weather will allow. You’ll be tired of eating the vegetables before the borer achieves his dirty deed.
If you can’t get the plants in early, try dusting the base of the stems weekly with carbaryl (click for sources) powder or spray them with acetamiprid (click for sources)
Using floating row cover is another excellent way to prevent damage. see Row Cover for Squash Vine Borer