Protecting farmworkers against injury and seeing that they get proper medical care, as needed, are growing priorities that have fostered a need for more training, says Gilbert Urquizu, supervising agricultural standards specialist with the Fresno County, Calif., Department of Agriculture, who discussed the topics at a Sanger workshop.

The event was sponsored by the San Joaquin Valley Winegrowers Association. Urquizu shared the program with speakers who discussed irrigation needs in a dry year and control of a major pest in grapes, botrytis.

Most of his talk centered on pesticide safety training, and a 31-point checklist of precautions to be taken when dealing with the materials. They included the admonition not to take pesticides home from work, potential hazards to children and pregnant women, and how and when to obtain emergency care. Other topics included decontamination procedures, routes by which pesticides can enter the body, and signs and symptoms of over-exposure.

It is important, Urquizu says, to maintain training records, to document when and where pesticide applications were started and completed, and to be sure that signs are posted around treated fields, as called for by the California Department of Pesticide Regulation. Records need to include the source of the material and who the trainer was. He also recommends mapping the location of field applications.

Information on DPR’s regulations is available at http://www.cdpr.ca.gov/docs/whs/psisenglish.htm

Going back five years, Urquizu says, workers had to be trained on about 10 points and the training didn’t have to be documented. All has changed as a result of increased regulation from both the state and federal governments.

Larry Williams, Department of Viticulture and Enology at the University of California at Davis, discussed wine grape water demand. Challenged by low rainfall in the past year, he says wine grape growers should take into account the amount of water that actually goes into the soil and the amount that can be lost to weeds or cover crops.

Williams, who works at the Kearney Agricultural Center at Parlier, says a cover crop can reduce soil water by 40 percent, and he offered a formula for calculating the “effective rainfall figure,” while stressing the importance of early irrigation

As the season goes on, he says, it is important to calculate evapotranspiration using data from the California Irrigation Management Information System and its array of weather stations.

Closer row spacing results in greater water use, Williams notes, and different trellis types result in different water demands. The gable trellis on 11-foot row spacing requires 52.1 inches of estimated seasonal water use; the 2-foot crossarm requires 35.7 inches; vines with quad corns require 35.9 inches; California sprawl requires 32.2 inches; the lyre type trellis takes 30.7 inches; and the vertical shoot position trellis takes 21.7 inches.

Some deficit irrigation can bring higher quality to wine grapes, he says, and regions such as Sonoma and Napa routinely seek to stress vines for that reason. Timing of applications is also important. Williams says; early season stress can significantly reduce berry size and yield across cultivars, compared to late season stress treatments.

Workshop participants also heard of the challenges in controlling botrytis, the pathogen that causes gray mold or bunch rot. Control requires chemical fungicides, and the disease can develop resistance easily, say Seiya Saito, post-harvest specialist, and Rachel Naegele, grape specialist, both with the USDA Agricultural Research Service at Parlier.

Saito discussed a rating system developed by the Fungicide Resistance Action Committee that shows the risk of resistance to various fungicides. A table shows that chemicals with the active ingredients azoxystrobin and pyraclostrobin have a high resistance risk.

Those with a low to medium risk of resistance include fludioxonil and fenhexamid. Fungicides with the highest frequency of botrytis include boscalid and pyraclostrobin.

Fungicides to control powdery mildew were also ranked. None of those listed showed a low risk to resistance. Those that had high risks included azoxystrobin, pyraclostrobin, kresoxim methyl and trifloxystrobin.

Saito says fungicides to control fungal diseases such as powdery mildew can impose selection pressure to botrytis for development of resistance, and that gray mold is a major post-harvest disease.

Naegele says tests can be done to determine the extent of resistance to multiple fungicides.