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Friday, June 22, 2007

Vine detective strikes out

So many things can go wrong in viticulture that I'm often amazed when growers bring a crop of gorgeous fruit to harvest. Region, of course, plays a huge role in the process, and I do happen to live in one that offers added challenges.

But I suppose this is also part of the attraction in the challenge of growing wine grapes. It's not so much Man vs. Nature as it is Man achieving a balance with Nature. In our climate-sealed bubble worlds where we slide from home to vehicle to office and back again, we might think we've got the natural world licked. The only growing things in our domain are the potted plants of our choosing. Any fauna appearing are pets, or otherwise they are immediately exterminated as pests.

But when you're growing grapes in the out-of-doors, you submit yourself to the gods of Weather and Sunlight. You are at the mercy of the crawly creatures that slip out of the forest and across the road under cover of darkness and feast on the literal fruits of your labor. I awoke one morning last summer to find a doe and her fawn munching on Traminette clusters as if I'd arrayed these grapes especially for their benefit. They'd eaten the equivalent of fifteen bottles of wine in one night. But then I'm growing my vines in her world and not mine...outside the sealed gasket of our house things are largely out of my control. And this is how it should be. It's almost comforting to be humbled by the natural world.

I recently set a tissue sample to the lab in order to diagnose the condition evident in the above photo of a Chambourcin leaf. Nature was turning on me, attacking my vines with some fungus, or robbing them of some needed nutrient. I decided that the condition doesn't match the profile of any diseases and seems more like some sort of mineral deficiency rather than a blight. I sent a tissue sample to the lab to confirm my assumption. But when I received the lab results (see below) for my tissue analysis, and everything seems mostly in balance (see Plant Analysis table).

I expected to find some glaring deficiency that I'd be able to correct by throwing a handful of this or that on the soil, or by spraying some substance onto the leaves. But from these results it looks like I was wrong and I am now left to wonder what caused those spots and the reddish tint on the leaves.

But another facet of the natural world, one we often forget in this age of the slash and burn, cement parking lot mentality, is her unmatched ability to heal herself. The blighted Chambourcin leaves seem to be dropping off now. New growth on these vines looks bright-green and healthy. Perhaps the best I can do now is to let Nature take her course and leave it alone. And maybe cross my fingers, too.

Lab Results
Nitrogen (N) -- 1.014%
Phosphorus (P) -- 0.570%
Potassium (K) -- 1.936%
Calcium (Ca) -- 1.418%
Magnesium (Mg) -- 0.642%
Iron (Fe) -- 5.1 ppm
Manganese -- (Mn) 38.1 ppm
Boron (B) -- 26.66 ppm
Copper (Cu) -- 10.2 ppm
Zinc (Zn) -- 36.3 ppm

Compare these results to the Plant Analysis table on this page to see how they match up. I'm a little low on iron and a bit high on phosphorous, but otherwise I'm within expected ranges.


David said...

I've had the same problem on my Chambourcin here in Oklahoma, however, it was much worse. I tried all the fungal and mildew sprays to no avail. Finally, hit the vines with malthion, sevin, and a spider mite spray and the infestation stopped. I concluded that it was some sucking insect biting the backs of the leaves.

DB said...

Interesting...thanks, I'll surely give that a try. I have such intermittent and random insect damage that I usually neglect these sprays and focus on fungus.


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