In spite of an unusually cool summer in Northern California, we seem to have plenty of vigour in the vineyard. The results from the petiole sample I took at bloom, came back within normal ranges (except for a slight Boron deficiency in the Cabernet sauvignon vines.) The combination of available nutrients, ample rainfall last winter, and a fair amount of sunshine, (despite Vinomakers griping that this summer is the coldest he has ever had the misfortune to live through), the vines seem to be finding everything they need to succeed. All in all, the vines appear to be in a fairly balanced state.
However, in a vineyard there will always be a few areas of over achieving vines, so I spent most of the afternoon hedging the enthusiastic sun canes, on the east side only. As I came around the last row I was met with the heady aroma of hot, sweet, luscious brambles. I stopped to admire the abundant crop of blackberries flourishing on the banks and the bed of the small creek that runs along the property line. I invested in a quick snack of sun-warmed, sweeter than sweet berries until my thumb and forefinger were stained a deep purple, a shade not unlike the almost squid ink-like hue of a good Petit sirah.
The Himalaya blackberry (Rubus armeniacus) is the most common, and prolific, non-native bramble in this part of California. It seems to have taken it's reputation to heart and has flourished along the length of the creek, through the wire of the deer fence and is rambling it's way towards the stationary rows of vines. Aside from the fruit being delicious, this tangle of evergreen growth provides another favourable component to Vinoland; the promise of a fatal demise for the Grape Leafhopper (Erythroneura elegantula.)
The GLH is a major pest of grapes, vines can tolerate a fairly large population but left unchecked GLHs can infest an entire vineyard. The GLH feed on the leaves by puncturing leaf cells and sucking out the contents. As injury to the leaf structure increases, photosynthetic activity declines...no photosynthesis, no sugar, no alcohol.
The most important natural enemy of the GLH is a tiny, almost microscopic mymarid wasp called Anagrus epos. These wasps are particularly valuable in the vineyard for their amazing ability to locate and attack GLH eggs. The fact that they can parasitise 90% or more of all GLH eggs makes them a very welcome and beneficial wasp to have around. Anagros bolsters it's numbers of egg laying adults in the spring by first parasitising the eggs of the Blackberry Leafhopper (Dikrella californica), thus ensuring it is more than ready to take on the GLH in the summer months. Thank you little waspy.
Phew! That was a long post...now where is that tub of vanilla bean ice cream?