For example, Botryosphaeria dothidea has caused active disease on citrus in Kern County for many years, so we know the spores have been blowing around Kern County for some time. Botryosphaeria panicle and shoot blight is more of a concern for pistachio this season since our rainfall accumulation has been similar to what the Sacramento Valley normally receives and where Botryosphaeria blight has put the future existence of the industry at risk in some counties. This year could well be the year when we see some active infections of this disease in Kern County. We continue to be limited as to what we have available to chemically control this disease, anyway. The Section 18 for multiple applications of Elite 7 fungicide was issued for this season and preventative applications may be warranted in orchards in Kern County where Alternaria late blight has been a problem or in orchards that have tested positive for Botryosphaeria dothidea , especially if the weather remains wet.
Elite works better as a preventative treatment as opposed to being a curative treatment.
Generally though, there is little evidence to suggest that spraying for Botryosphaeria dothidea in Kern County is necessary or desirable or, in fact, that Botryosphaeria panicle and shoot blight will occur in this county at an economically significant level this year. For those not wanting to make preventive Elite treatments with so little idea of the need or risk in Kern County, it may be prudent to look for disease symptoms in suspect orchards early in the season. Themis Michailides writes that wilting shoots first appear in late April, early to mid-May, and during June. Infected shoots quickly turn black and their leaves wilt and die. Infections on fruit clusters turn black, usually starting at the basal or branching points of the rachis.