Fungicide update for blueberries
There are several important changes to fungicide labels for blueberries that are described in this article.
The fungicide Quash (metconazole) now has a supplemental label for blueberries. This label must be in the possession of the grower at the time of application. Quash is also labeled for other small fruit crops belonging to the bushberry group, such as gooseberry, currants, Saskatoon berry and aronia berry. This fungicide belongs to the sterol inhibitor (SI) fungicides, which constitute the Fungicide Resistance Action Committee group 3, so it has the same mode of action as Indar and Orbit.
In multiple trials, the efficacy of Quash has been similar to or slightly better than Indar for mummy berry. However, it appears to have a broader spectrum than some of the other SI’s. For instance, Quash has efficacy against anthracnose fruit rot, Phomopsis twig blight and canker, Botrytis and leaf rust. Leaf rust efficacy of Quash is similar to that of Indar and Orbit. Quash can be applied at 2.5 oz/acre on a 7-14 day schedule and has a seven-day pre-harvest interval (PHI), which is shorter than that of Indar and Orbit. Do not apply more than two times sequentially and three times total per season. Adjuvants may not be used with Quash in blueberries or any of the other bushberry crops.
Cabrio and Pristine
There have been some changes in the labels of Cabrio (pyraclostrobin) and Pristine (pyraclostrobin + boscalid) for blueberries due to a lawsuit in California alleging phytotoxicity to blueberries. It should be pointed out that there are no reports of phytotoxicity of Pristine or Cabrio on blueberries in Michigan or other states in the eastern United States, so we do not anticipate problems with these materials.
Blueberries were dropped from the Cabrio label; product with the old label can still be used as the residue tolerance for pyraclostrobin remains in effect. For Pristine, there is now a supplemental label available which allows Pristine to be used on blueberries and caneberries with certain restrictions. This label must be in the possession of the grower, in addition to the container label, at the time of application. The supplemental label for blueberries and caneberries stipulates that Pristine should be mixed only with water and must not be applied as a tank-mix with any other pesticide products (including fungicides, insecticides, herbicides), adjuvants, liquid fertilizers, nutrients, or any other additives.