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6 4 V I N E YA R D & W I N E RY M A N A G E M E N T | M a r - A p r 2 014 w w w. v w m m e d i a . c o m first pruning cut that may have con- tacted spores. If left in place, canker diseas- es move down the vine toward the trunk. This movement occurs at different rates, depending on the pathogen. Gubler said Eutypa can move up to 2 inches per year, whereas Bot can move 5-7 inches per year. Vineyard sanitation is also impor- tant. Deadwood cut from vines and prunings that can be infected if left on the ground, should be removed so they do not harbor fruiting bod- ies that produce spores. PRUNING WOUND PROTECTANTS If a grower must start pruning in December due to large acreage or labor scheduling, applying a prun- ing-wound protectant right after pruning or prior to the next rain can be a good control option. "Topsim M has shown to be an effective pruning-wound fungicide over the most species," Gubler said. "We recommend a solution of Topsin M plus Rally to provide two modes of fungicidal action." One drawback of these fungicides is that they may only be effective two weeks, or until the next rain, and may need to be reapplied until the wounds heal. A newer product registered for organic use that can protect up to three months is Safecoat VitiSeal, a water-based sealer with natural plant oils that creates a barrier to block pathogens from entering the wood. Several North Coast growers use this product, hand-applied by daubing it onto pruning wounds by a worker who follows a hand-prun- ing crew. VitiSeal and other wound protectants can also be applied by hand- or tractor-sprayer. "With these diseases, you can either spend money up front, or at the end," Gubler summarized. "If you spend it up front, your vineyard will have a longer life." Another aspect of the USDA project is an evaluation of the long- term cost-effectiveness of the dif- ferent prevention practices, and the potential of early-detection tests to give growers economic information to make management decisions. Ted Rieger, CSW, is a writer and photographer based in Sacramento, Calif., and has been a contributing editor for V&WM since 1990. Comments? Please e-mail us at feedback@vwmmedia.com. All grape varieties are sus- ceptible to canker diseases, but some can be more sus- ceptible than others. Based on anecdotal field observations, v a r i e t i e s c o n s i d e r e d m o r e susceptible to Eutypa are cab- ernet sauvignon, syrah, pinot noir, chardonnay, riesling, sau- vignon blanc and chenin blanc. B a u m g a r t n e r a n d o t h e r researchers looked at can- ker formation susceptibility in a lab and greenhouse study with cabernet franc, caber- net sauvignon, chardonnay, merlot, riesling, petite sirah, Thompson seedless and Con- cord from seven trunk patho- gens. Thompson seedless was found to be more susceptible to Eutypa and Phomopsis; the six vinifera varieties and Con- cord did not vary significantly in susceptibility to Eutypa, Bot canker and Esca. VARIETY SUSCEPTIBILITY This vine shows pruning wounds and cut cordon painted with Safe- coat VitiSeal, which protects pruning wounds from fungal infection. Photo: Ted Rieger