I started a grape arbor last year and I was hoping to sample a few grapes (Somerset Seedless, Jupiter, and Steuben) this year after some significant thinning. Everything has been going as planned, but when I got back following a 2 week absence, I realized that something was amiss, as I had some grapes changing color and shrinking. I identified the problem as a new foe: the grape berry moth.
There is plenty of available info on GBM on Cooperative Extension websites, but I was unable to find anything from/for backyard growers (including this discussion list). I would like to eradicate the moths effectively with an insecticide with the smallest footprint. I currently have Bt, Spinosad, and Sevin. Does anyone have a recommended spray plan that would help with the current infestation as well as future generations? I am located in Northeast Pennsylvania. Many thanks!
I would try acetamiprid. Its an Ortho Bug B Gon product. Its labeled as being “systemic” which supposedly means that it works from inside the plant. Should kill the the larvae that hatched out from the eggs that the moth laid. I’ve got an arbor too and I find it difficult to spray the grape clusters that is against the boards of the arbor. That is where most of my insect damage is on my arbor.
Its drawback is that it is expensive. And, I am not sure about its environmental impact but it seems safe to me.
If you just planted your grapevines the spring of 2016, you really should limit the production of the vines this year. In fact, most growers won’t let their vines produce until the third or fourth year. But I must confess, I usually violate that rule too.
Thanks, Sam. Acetamiprid sounds very effective. I had never heard of it before now. I am a bit concerned about the impact it may have on the nearby bees as it is a neonicotinoid. Immediately next to the arbor is a part of my garden which has borage and arugula that is in bloom which is swarmed by bees at the moment. I may have to use something less effective on the GBM and apply multiple times if I am going to try to keep the bees safe.
I spent some time pondering if I should prune all grape clusters this year. I did see a few liberal recommendations that I thought might be reasonable. I ended up only keeping one cluster for every 2 vigorous shoots. I also tip-pruned each of the clusters. I may not end up with many grapes at the end of the season, but at least now I will be ready for the GBM next year!
Of the three vines that you have, the only one that I have is the Jupiter. If that grape is allowed to fully ripen to a really dark blue-black color it is really yummy with the skin being very eatable. My problem is that I nearly always pick it long before its fully ripe because of the birds. I’ve got 4 Jupiter vines and they are generally healthy except one had some die back this past winter. Always have spur pruned them. Think I need to reduce the number of cordons on a couple of my Jupiter vines b/c of short shoot growth resulting in small grapes. Hard to figure out exactly where to arrange the cordons on an arbor. I neglected to thin this year and that did not help either. Got plenty of grapes this year but am concerned about my vines this winter. Disease problems seem minimal except Jupiter vines are very susceptible to downy mildew. Very productive vine with large grapes if managed properly though.
Concerning spraying, I try to always spray right at dusk to minimize the effect on the honey bees.
YES! I have been hit by downy mildew late last summer and recently this year on the Jupiter grapes. I have got to improve my captan spray timing. I am not sure why, but my Jupiter grapes are very sparse compared to the other two varieties (but large, like you said). The downy mildew never got too bad and there were not too many hits of GBM on Jupiter. Maybe the fruits abort with less stress than the other varieties.
I am starting to wonder if the gooseberries that were aligned along the east side of my grape arbor could have also been infested with GBM too (see previous thread: Gooseberry problem ). I had a good crop going, but most of them split or matured prematurely, and I did see a worm/larva inside one of them that looked near identical to the GBM. Does anyone think that the moths would develop a taste for gooseberries? Obviously, the two fruit types are very similar in form.
I found a link that suggests GBM also feasts on other edibles, including gooseberry: http://www.plantwise.org/KnowledgeBank/Datasheet.aspx?dsid=42794
After reading about gooseberries thru wiki, I now know what a gooseberry is - or at least I think I know. Hmm. lol