An automated system was developed and tested for delivery of thick latex paint to a pruning wound at the time of pruning. The system works by coating the cutting blade of a pruning shear with fluid and then fluid transfer from the blade to the pruning cut. There are several major components to the system including a fluid pump, a solenoid valve actuated by a proximity sensor on the pruning shears, and pruning shears modified to allow fluid to be delivered to the cutting blade. The pruning shears can be manual shears or electronic shears. Variables tested in the proposal were blade type, fluid viscosity and fluid flow rate. While the system delivers fluid effectively to the blade, at fluid flow rates greater than 1 ml per pruning cut, fluid tends to leak from the shears. We believe the shears can be modified to prevent leaking.
The pathogenicity of Botryosphaeria obtusa and Eutypa lata isolates from symptomatic cankers was assessed using two-year old vines. Vines were inoculated with mycelia and the resulting lesion length measured after one month of incubation. The lesion lengths for B. obtusa isolates and E. lata isolates were 50.7 mm and 36 mm, respectively. Both were significantly different from the control, and indeed the data indicate that B. obtusacolonizes grapevine tissue more rapidly than E. lata. Koch?s postulates were completed by recovering the inoculated pathogen from the margin of the symptomatic tissue. The data indicate that B. obtusa is a pathogen of grapevine.
Trunk damage associated with mechanical harvesters is a potential infection site for vine pathogens. Of the 36 trunks examined, 33 had damage associated with mechanical harvesters. Twenty-eight of the vines with this type of damage had B. obtusa isolated from cankers associated with the damage. We examined the asymptomatic tissue at varying vertical distances from the canker margin to determine if B. obtusa was the pathogen at the advancing front of fungal colonization and if there were other pathogens associated with the canker. However, the prevalence of other wounds, particularly from shoot removal from the trunks, made it difficult to determine how far B. obtusa could be detected from the canker margin in asymptomatic tissue, and if sampling location biased pathogen diagnostics.