With spring coming fast, growers need three eyes —should one to watch the thermometer, another to observe the sky, and a third to monitor the crop for potential disease problems.
“There is nothing much to report now,” says Doug Gubler, UC plant pathologist. “If the spring is cool and wet, mildew might be early this year.”
Other less-heralded diseases are becoming more a concern, with more species being identified eachyear. Multiple species of fungi from the Diatrypaceae family, which includes Eutypa, Botryosphaeria, and others, have been confirmed in California.
UC recommendations for Eutypa dieback include making large cuts directly after a rain, when the risk for infection is lowest.
Botryosphaeria inoculum can affect a vineyard from nearby tree crops such as almonds, pistachios, and cherries. Bot canker species infect pruning wounds and are particularly infectious to vines during periods of rainfall.
Esca occurs when ascospores are released from fall through spring, usually after rainfall. Infection can occur under a range of temperatures. The spores re-infect the vine through pruning wounds, which can remain susceptible up to 16 weeks.
“Double pruning or late pruning is still the best way to escape infections from Eutypa spp., Botryosphaeria spp. and the esca pathogens,” Gubler says.