Jacob- you might minimize some of the damage by keeping the plants covered with floating row covers until they start to flower. I have not found any maps showing the information you’re looking for either. Everything I’ve read suggests planting as late as possible and using row covers.

Jacob - up here they emerge in early to mid June into July so I'd guess it may be a week or 2 earlier down there, I'm not sure if north Arkansas is far enough south for SVB to have 2 generations a year. Last year I planted winter squash in early June and didn't have a problem with them. Squash bugs yes, SVB no.

Pretty simple. Just get in touch with your local extension service. They'll know. In my part of the world, we get two emergences per year. One in March, and the other in May. They are gone by July. So that's when I plant out. Of course, my growing season is very long, so I have loads of time for productivity before the first frost in December.

Here in north central AR they start to show up around June 10-12th. All my squash have floating row covers but I could usually remove them by mid-July if I wished and I can put out new plants mid-late July.

Dave

Thanks everyone! I may check with the extension office.

Dave, sounds as if we're fairly close, so I'd assume we'd be close to, if not completely, on track in terms of SVB. I think I'll just do floating row cover, as I'd prefer to have a crop earlier than Sept.

Thanks again. A map on this topic, even for more than just SVB, sure would be handy. What a tool that would be...

I was reading an article the other day about squash pests (I do not have the link handy at the moment) and it suggested that squash vine borers don’t often affect large-scale commercial growers and, consequently, there is not a lot of research into co trolling them beyond the measures small-scale and home growers take. It makes sense, in that when more money is involved, more people are interested in a topic.

I’ll see if I can find that article again.

Very good point. A map showing SVB-proof planting dates would be enormously useful.

I wonder if there is a correlation between their emergence and soil temperature. I think that there is probably a direct correlation, and , if so, a temporal map of soil temperatures might be a proxy for SVB moth emergence.

Jamie, that's true....For example maybe in July the soil is just entirely too hot for them to thrive, and come autumn, there isn't enough warm weather left for them to really have a second season. And then Dan said in Texas they have a SVB emergence in March and May, which would make sense considering they have possibly a longer spring most years?

I suppose there's only one way to find out whether this is true...I'll leave a plant out and let it get hit, measuring the soil temp when they come. Then I'll do the same next year.

I believe the SVB egg-laying schedule is determined by degree-days. As in, egg-laying allegedly happens when you reach DD50 of 1000, according to a number of references. Laying of eggs, rather than emergence, is the key threat here. DD50 is the total number of degrees over 50F (average daily temperature minus 50F) accumulated (negative numbers don't count) as the year goes by. Anyone know where to get mean DD50 as a function of date for different locales? It would be interesting to compare that with SVB experience of individuals.

Not sure how that pertains, however, to two-generation locations. That would predict, I guess, the date of FIRST egg-laying. Not the second. Though I suspect the second is a fixed number of days after the first.

I would bet that the second is a set number of days also

Dan- this site will calculate degree days for any base temperature for weather stations around the country.

http://www.degreedays.net/

i can’t download the results for my area because I’m on my phone now.

Thanks. The way you use that tool to get DD50 is you select "Data Type"="cooling", and Base Temp=50F, and you add up the numbers, starting at the beginning of the year. Now, that tool gives you the degree days for the last year. It does *not* work with climate averages. For planning, climate averages would be more useful. But if you want to know when to start SVB avoidance THIS YEAR, then this tool is helpful.

For me, I get that DD50=1000 happened around the beginning of April this year, which is pretty consistent with my understanding for the onset of SVB troubles, based on my own experiences and dates I've read about from my extension service. I've always assumed March for first SVB troubles, but it was definitely a cool spring this year. So I suspect we'd normally hit DD50=1000 somewhat earlier if looking at climactic averages.

I didn't have any squash out then, so I'm not able to validate the DD50=1000 trigger for this year. This tool tells me that if I had squash out this year, I should have started SVB mitigation at the end of March.

Might there be a DD50 generator out there that works with climactic averages? That is, the AVERAGE mean temperature for each day of the year.

You can get climate average mean monthly temp as a function of month here ...https://www.melissadata.com/lookups/zipweather.asp . So that's a crude way of getting there.