Quote:My area of expertise lies with vineyard but I grow almonds (I'm mainly just the idiot on the tractor) and a small amount of pistachios as well.


In grapes, the main area of concern during the growing season is powdery mildew. To keep it from developing we use fungicides, but we also have to be mindful of resistance development. I guess you can think of it along the same lines as taking antibiotics.


There are biologicals, contact fungicides, multi-site, strobilurins, sterol inhibitors, and cell signal inhibitors. They all have different modes of action, some don't allow resistance while others do, sometimes as soon as after two consecutive uses. The Fungicide Resistance Action Commitee (FRAC.info) will assign a FRAC number to each mode of action, so we are more easily able to distinguish between the different groups.


Taking this info into consideration, a grower will have to build a very carefully planned pest management program taking this into account. If you let resistance develop, not only will you lose your crop that year (and thus, make $0 AFTER you spent $__ amount the whole year in order to grow), you could even possibly have to pull out your whole vineyard and start fresh -- potentially losing like 5 years of income.


That's just the most immediate consideration. There's also the actual working method. Some wash off in rain, some are only effective in temperatures above 90 degrees, some are contact only while others re-distribute themselves, some last 5 days and some 3 weeks -- and so on and so on.


Then you have your pesticides which is just as complicated. We also deal with degree days, chill hours, ionic charges, soil bonding, ph, plant nutrition and plant genetics. It goes on and on.