Squash Leaf Curl Virus

Asked August 27, 2020, 7:14 PM EDT

My butternut squash grew like crazy until about mid-August then just stopped growing. I noticed that the edges of leaves were curling. Online, I found that they are probably infected with SLCV. I'll still get plenty of squash for us, but my big concern is that I planted these squash in my chicken litter/garden soil compost pile. Will this virus overwinter in the compost, so that I can't use it next year for cucurbits?

Benton County Oregon

1 Response

Hello there. I have researched virus diseases found on squash in the Pacific Northwest and there are three that are most prominent. Unfortunately, the PNW Plant Disease Management Handbook does not mention Squash Leaf Curl Virus. Zucchini yellows mosaic virus (ZYMV), watermelon mosaic caused by Watermelon mosaic virus 2 (WMV2), and curly top caused by the Beet curly top virus (BCTV) are the three most common. The first two are found west of the Cascades and BCTV is found only east of the mountains. Viral diseases have multiple plant hosts that can include ornamentals, vegetable crops, and weeds. They can be spread by insects such as aphids, whiteflies, leaf hoppers as well as thrips, or even cucumber beetles. Some can also be spread by tools, physical contact and in some cases seeds. They can only definitively be diagnosed with an electronic microscope or with serological studies of the plants. If the fruit of your butternut squash has not been affected and looks normal your plant could have another problem other than a virus. If your plant does have a virus you could be risking spreading the virus to other plants in your garden by not pulling the plant. Viruses only multiply in living cells. Once the plant is dead you should be able to incorporate it into your compost pile with out concern of spreading it. I found information on SLVC from Texas A and M University, it is spread by whiteflies and not by seed or mechanical means. If your plant has another type of disease it is possible that the disease could survive on dead plant materials in a cold compost pile over winter.