Have you ever grown garlic or onions and been distressed to see that the plant has stunted gnarled, yellow streaked leaves? Upon closer inspection, you don’t really see any insects. Well, it’s quite possible they’re there but just too small to see without a microscope. You are probably looking at wheat curl mite damage. What are wheat curl mites and what wheat curl mite control is there? Read on to learn more.
What are Wheat Curl Mites?
Wheat curl mites (Aceria tulipae) are tiny, almost microscopic plant feeding mites. They have 2 pairs of legs near the head which is perched atop a cigar-shaped body. Their favorite food, as the name suggests, is wheat, but they also infiltrate fields of onions and garlic.
Wheat curl mites on plants become active in the spring and their populations virtually explode as temps increase; 75-85 degrees F. (23-29 C.) are prime reproduction temperatures. They lay their eggs in rows along leaf veins and when conditions are optimal, an entire generation can be completed in 10 days.
Wheat Curl Mite Damage
Not only do wheat curl mites cause twisted, yellow streaked leaves, but their feeding causes onion and garlic plants that are being stored to desiccate. Equally as damaging, wheat curl mites act as a vector for Wheat Streak Mosaic Virus, which is one of the most destructive diseases of wheat crops.
They are also vectors of the High Plains Virus, which afflicts both corn and wheat in the Great Plains region, and Triticum Mosaic Virus, which is often seen in conjunction with Wheat Streak Mosaic Virus and can decimate a crop.
Because of the serious damage and loss of capitol, treating wheat curl mites is of paramount importance. Sadly, there is very little wheat curl mite control at this juncture.
Wheat Curl Mite Control
Wheat curl mites on plants are found on the terminal leaves and move onto each new leaf as it emerges. Once the wheat dries down, the mites gather on the flag leaves where they are picked up by the wind and carried to other food sources, such as other grasses and corn.
Once these die back, the wind carries the mites onto newly emerged winter wheat. Wheat curl mites can live for several days at temps below 0 degrees F. (-17 C.) and for several months at near freezing temperatures. This means they are present for an extended period of time, and ready and willing to do significant damage to successive crops from spring into winter. So how do you go about treating wheat curl mites?
There are no blanket controls for wheat curl mites. Flood irrigation in commercial crops or heavy winter rains can reduce field populations. Commercial growers treat seed garlic with hot water to reduce seed infestation and destroy volunteer wheat at least two weeks prior to planting winter wheat. No chemical treatments have been determined to eradicate the mites.
Most home growers don’t plant wheat, but many of us grow onions and garlic. Don’t plant successive onion or garlic crops in the home garden that will just begin the mite reproduction process anew.
Treat bulbs prior to planting with hot water to reduce the population of mites. Soak the bulbs at 130 degrees F. (54 C.) for 10-20 minutes or at 140 degrees F. (60 C.) for 10-15 minutes. You can also try soaking affected garlic cloves for 24 hours in 2% soap (not detergent) and 2% mineral oil solution. Some sites suggest soaking cloves in alcohol for a few minutes prior to planting to kill any adult mites.