Last post I shared some thoughts on pests and diseases in the vegetable garden. Maybe I should never have mentioned the squash vine borer, because Friday evening I came home and found the Honeybear Acorn squash in dire straits:
All the evidence points to the borer - perfectly healthy plant one day that collapses the next as the borer eats its way into the vascular system of the plant. Now there's a remote possibility that this is bacterial wilt, but wilt kills the plant over several days, as the plant partially recovers in the morning then gets progressively worse every evening. There is another Acorn squash behind this one that is also susceptible to the borer. The remaining squash are Butternut and Teksukabotu, and they both have hard stems that are usually impervious to the borer.
I haven't pulled the plant up yet, it's still showing some signs of life. It has produced three nice Acorn squash. Being dark green and full-sized they look ripe, but Acorn squash need 40 to 50 days from fruit set to reach full ripeness, in other words to develop their sugars fully. So these probably need another month on the plant which will probably expire any day now.
I still plan to harvest the squash once I pull the plant up and at least try to prepare one of them. I expect the squash to be waterry and starchy, but it's worth a try. This article from Johnny's Seeds has some excellent advice on when to harvest and how long to store winter squash: http://www.johnnyseeds.com/t-eating_quality_in_winter_squashes.aspx
My prevention methods for the borer consist of spraying the stems with Bt twice a week once 900 growing degree days, base 50 F, have been reached (early June here) and continuing this program for about three weeks. As this shows it's not foolproof, but at least my summer squash plant has not been affected, yet.