As the bloom begins, it's important to keep an eye out for this pesky pair: brown rot and shot hole. Resistance to the newer fungicides has not been found in almond populations against either of these diseases, but the potential is there.
Studies last season identified several highly effective fungicides and fungicide premixtures for the management of brown rot blossom blight and shot hole. Use them in rotation or in tank mixes for greatest efficacy and to prevent resistance from developing.
The most recent registrations include Ph-D, a polyoxin and reduced-risk fungicide; Inspire and Quash, sterol biosynthesis inhibitors (SBIs) with a single-site mode of action; the premixtures Quilt Xcel (a QoI and an SBI); and the natural products Regalia and Actinovate. Inspire Super and Quadris Top are pending registration this spring. Check with a crop protection professional for the latest on registrations for the 2011 season on almonds.
Brown rot blossom blight
The most effective new fungicides for this disease are Adament, Luna Sensation and Quash. Research has also shown success with premixtures such as Inspire Super, Inspire XT and Quilt Xcel.
Syllit, Quadris Top and Quilt Xcel are new fungicides that have shown a knack for knocking out shot hole.
The finer points
Efficacy trials for these products were conducted by Jim Adaskaveg, plant pathologist at UC Riverside. You can access his research report to the Almond Board of California and his poster on the same subject, which was displayed at the Almond Industry Conference in December, at the ABC research report database. Search the database by "Researchers" and choose "Jim Adaskaveg." The research report number is 09.PATH4.Adaskaveg, and the poster is 10.PATH4.Adaskaveg.