This past fun-filled weekend we had to hurriedly prepare a spray for the vineyard, only to have our sprayer malfunction in the worst possible way — two strainers in the back blew out from the strain of the pressure. Our air blast sprayer (produced by a company called Air-o-Fan) run at about 100 pounds per square inch, and the strain on the strainer takes its toll. One blew out, and we thought, no problem, because we had one extra. Drove back to the barn, put on the new one, returned to the vineyard, cranked it up — and the second strainer blew (there are two). No replacement for that one, which mean’t no spraying that day. We’re experiencing severe disease pressure — what to do?
Indeed, what to do? We had a wine festival in Richmond the next day, and the day after on a plane to California to visit family and friends for a graduation at the University of Southern California, first swinging through San Francisco to see relatives and a fabulous dinner planned at Restaurant Gary Danko on North Point in The City (more on that later). We’ll be away a week and can’t delay a fungicide application, with our Phomopsis problem lurking in the vines. A few quick calls secured replacement parts (a half dozen) from the manufacturer, which will be overnighted, and calls to our beloved neighbor who tends to the fields and keeps an eye on things (but has never run the sprayer) took care of our other problem, which is to make sure we applied a treatment very soon, not that the rains have passed, for now. Russell came on over 20 minutes after our rather frantic phone call, had a quick tutorial and instructions on operating the thing. Many thanks to Air-o-Fan (and to Russell) for coming though for us!
Saturday proved a bit forbidding, with violent thunderstorms in the forecast that were to peak mid-afternoon. But the storms missed us, and it was a rather pleasant afternoon at the Snag A Job Pavilion in Glen Allen for the Central Virginia Wine Festival, an event put on by the Richmond Virginia Tech Alumni Association, a fundraiser for scholarships for Richmond-area students attending Tech. Fabulous cause with fabulous people running it. And the volunteers! We had teams assigned to us to help pour (they were in a word (and we’ll say it again) fabulous — such enthusiasm, such grace and good cheer! And of course they loved the wine (how could they not?), and purchased several bottles on top of the wine we gave them as a thank you gift for helping. The festival staff helped us unload, and when it was over they loaded us up to go (we were among the first out of there) — we felt like Princes.
Just before our sprayer mis-adventure on Friday, however, we looked down and spotted our first cicadas on the fence post at the gate to the vineyard. We are due to have a massive invasion of the periodic cicada this year, an event we look forward to with curiosity and dread. We didn’t see them in Richmond on Saturday, or up north in McLean on Sunday, but they are all over Annefield. When packing up to depart the next day for the festival we spotted dozens of them in the grass and crawling up the side of the house, many of them just emerging from their exoskeletons. Many that we saw had just emerged, with their crazy orange eyes, waiting for their shells to harden, milky white and vulnerable. They haven’t started singing yet.
Dr Tony Wolf of the Alson H. Smith Jr Agricultural Research and Extension Center of Virginia Tech Virginia circulated a memo about them (and included an ominous note that there is a threat of potential spring frost on Monday in the Shenandoah Valley) advising what winegrowers need to do about the 17-year periodic cicadas emerging this year — in a word, nothing.
Periodical cicada spends most of its life as a nymph, feeding on xylem sap from tree roots. In the final year of development, nymphs crawl from the soil, climbing tree trunks or any other structure. During the night, the nymphal skin splits along the midline, and the adult emerges. Adults appear in mid- to late-May (a few individuals may be heard as early as late-April). They appear around sunset, males slightly preceding females. Males congregate en masse in “chorusing centers”. Singing peaks around 10:00 AM. Adults feed on a wide range of woody plants during the day; such feeding is apparently restricted to the females because the male digestive tract is rudimentary. Egg-laying begins about 2 weeks after emergence. Eggs are inserted into twigs in groups of 10-25; the slit into which the eggs are inserted is 1-4 inches (2.5-10 cm) long. Females may lay over 500 eggs. Oviposition peaks in the early afternoon. Adults are active for about 6 weeks. Eggs hatch 6-10 weeks after oviposition, whereupon nymphs leave the twigs and drop to the soil. Nymphs tunnel to the roots where they establish themselves for feeding.
What threat do cicadas pose to grapevines? If you’re new to grape growing since the last emergence of periodical cicada’s you may think that the insects are causing significant damage, and your immediate reaction will be to ask what insecticide might be sprayed to keep the insects off your grapevines. While that’s an understandable reaction, my advice (TKW) would be to find something else to do and not worry too much about what the insects are doing. You are going to see shoot breakage and you may want to defer trunk and cordon establishment on young vines until next year, but grapevines are pretty resilient. Injury by egg-laying is a much greater problem than feeding is, but it’s helpful to realize that the egg-laying (ovipositioning) on mature grapevines is not as detrimental as it can be for young fruit trees or woody landscape materials, which you may wish to protect. The cicadas will deposit eggs in grape shoots and smaller cordons of the vine. Unsupported shoots often break beyond the point of egg-laying, but because this occurs relatively early in the growing season (June), lateral re-growth will normally compensate for the loss of a primary shoot tip. In older wood, the oviposition site typically heals.
Insecticidal control of cicadas is not very practical because of the extended period of emergence and activity (up to 6 weeks) and because insecticides would have to be applied very frequently to come in contact with newly emerging insects. Fine netting is an option mentioned in the above-cited Fact Sheet, but the economics of this approach with grapevines is questionable. Young (first-year) vines are a special consideration in that one is attempting to produce shoots to serve as trunks in the following year. One potential means of protecting the shoots would be the use of grow tubes, which would discourage cicadas from at least the first 24 to 36 inches of the shoot. Alternatively one might simply retain several shoots in the first year in the event that one or more shoots break during development.
They’ll put on a spectacular show.
Incidentally, at the Central Virginia Wine Festival, our newly released 2012 Annefield Vineyards Viognier was named best white wine at the event. We last attended this festival two years ago (we had a conflict last year) and received the same honor. We like to think they love us and we certainly love them. Its a great event, a worthy cause, and we’ll probably be back. next year. Go Hokies!