Magister SC Miticide from Gowan Company is now registered for use on many specialty crops. Although it is called a miticide because it controls spider mites and rust mites, it also controls some insects (psyllids and whiteflies), and powdery mildew on some crops. The active ingredient is fenazaquin. Its mode-of-action group as a miticide is 21A, the same group that contains Nexter, Portal, Torac, and Apta. Magister kills mite eggs by contact, and kills mite adults and immatures by contact and ingestion. For fungicidal activity, it is in FRAC group 39. Magister is highly toxic to bees, so care must be taken to not spray it on blooming crops or weeds.
Magister has been registered for a few years for use only on hops and cherries. Vegetable crops now on the label are cucurbits (3-day PHI), fruiting vegetables (3-day PHI), and legumes (7-day PHI). Small fruit crops now on the label are blueberries (7-day PHI), caneberries (7-day PHI), strawberries (1-day PHI), and grapes (7-day PHI). Tree fruit crops now on the label are pome fruit (7-day PHI) and stone fruit (3-day PHI). Hops are also on the label (7-day PHI). The label specifies a limit of one application per year on each crop, and a 12-hour re-entry interval. The rates are 24-36 or 32-36 fl oz per acre, depending on crop.
-Celeste Welty, Extension Entomologist