Rotate pesticides to avoid resistance
We use to recommend rotating pesticides to avoid resistance. We started saying to rotate between chemical classes 5 to 10 years ago. More recently, we have learned it is best to rotate between modes of action, which takes care of the chemical class. I created a handout and passed it out at meetings.
The best information on mode of action for all pesticides (to my knowledge) is on the OHP (formerly Olympic Horticultural Products) website www.ohp.com It is easily found and printed.
Each different mode of action is considered a group and is assigned a number. The mode of action group will begin appearing prominently on pesticide labels.
It is suggested for resistance management that the same insecticide or miticide not be applied to more than one generation of the pest per year. As a general rule when the label permits, make 2 or 3 applications of a labeled insecticide or miticide in sequence, then rotate to another recommended labeled product with a different mode of action.
The mode of action group number on the label will make it easier to choose pesticides with resistance management in mind.
? We are seeing a few blocks of plants that were damaged or weakened by last summer?s dry spells and perhaps December?s cold temperatures, I think. There is some tip dieback and even severe branch death. Some are slowly leafing out. Most of the plants are suckering, indicating that the roots did not totally die.
? New Insecticides and Miticides ? Flonicamid (Aria 50 WDG) has a new mode of action that inhibits insect feeding within one hour of treatment, eliminating the pest in 3-5 days. The mode of action grouping for Aria is called the selective feeding blockers. It is labeled for control of aphids, thrips, whiteflies (suppression only of silverleaf whitefly), and mealybugs in greenhouses on ornamental crops.
Another selective feeding blocker that has been around some time, is Endeavor. It was given a ?Reduced Risk? status by the EPA and exhibits safety to beneficial insects. Endeavor is labeled for control of aphids and whiteflies and has translaminar activity, which allows it to move from one side of the leaf (sprayed side) to the other.
Insect growth regulators (IGRs) target immature insects and mites. Some IGRs can also make the adults sterile. The chiten synthesis inhibitors prevent the formation of chiten which is needed for the formation of the insect or mite exoskeleton.
When treated with this type IGR, the insect or mite dies while trying to molt to the next stage. Diflubenzuron is an older compound (Dimilin) that is still effective that is now available for greenhouse use as Adept. There are three newer IGR compounds (Talus, TetraSan and Pedestal) available for ornamental use.
Buprofezin (Talus) is labeled for control of the nymph stages of whiteflies, scales (soft, armored, margarodid [such as cottony cushion scale]), mealybugs, planthoppers, and leafhoppers. It also suppresses egg-laying and causes egg sterility in treated adult insects.
Etoxazole (TetraSan 5 WDG) is labeled for the control of spider mites in the egg or nymph stage. It can be used on ornamental plants and non-bearing fruit and nut trees indoors (greenhouse, interiorscapes) and outdoors. TetraSan is not intended for residential uses. It also exhibits translaminar movement within the leaves. It should not be applied to poinsettias after bract formation.
Novaluron (Pedestal) is labeled for the control of thrips, whiteflies, armyworms and suppression only of leafminers. Pedestal should not be applied on poinsettias.
One mode of action grouping, called oxidative phosphorylation uncouplers, prevent the formation of a critical energy storage molecule, adenosine tri-phosphat (ATP). Chlorfenapyr (Pylon) is the only currently labeled product in this mode of action grouping labeled for use on greenhouse ornamentals.
Pylon is labeled for control of fungus gnats, foliar nematodes, caterpillars, spider mites, broad mite, rust mites and citrus rust mite. Pylon is not ovicidal but does exhibit translaminar movement in the leaf.
Spiromesifen is a new class of chemistry from Bayer Environmental Science with a unique mode of action. It is a lipid biosynthesis inhibitor that prevents insects from maintaining a necessary water balance.
Judo is available for use on greenhouse and nursery ornamentals. It is labeled for control of whitefly nymphs, pupae and all developmental stages of many types of mites including spider, broad, cyclamen, false spider and rust mites.