Growers Should Manage Pests by Watching Closely

Look what I caught in my sweep net: Thrips and aphids.

The nice weather is good for young cotton plants – and pests too. I’m starting to spot small amounts of spider mites and thrips in the cotton fields as I make my rounds scouting fields across the Valley.

Thrips will feed on leaves and buds and may cause seedlings to become deformed. But the hot weather will help plants grow out of the damage. Growers and UC Integrated Pest Management experts believe thrips do more good than bad because they will prey on mites. For a discussion about this pest, read UC IPM advisor Dr. Pete Goodell’s blog about western flower thrips.  The weekly MiteFax report by Owen Taylor features more information about thrips by UC extension cotton specialist Bob Hutmacher.

One bad bug is the spider mite. The pest can cause leaves to turn yellow or red and fall off. Losing leaves reduces the amount of energy for the plants and may cause squares and bolls not to develop fully and end up dropping to the ground.

Water trucks will keep the dust down.

In the past couple of years, I haven’t seen any major mite outbreaks. I attribute a lot of that to good preventative measures taken by our growers. Dust control, for example, is an important measure to keep mites under wraps. Growers are doing a good job with water trucks wetting down the dirt roads around their fields once or twice a day. Managing dust helps prevent mites living on dusty roads from being disturbed and blown onto plants.

So far, the cotton plants are at second and third true leaf on the westside. In the Dos Palos area, plants seem to be developing faster and are on their third or fourth true leaf.

Overall, by my count, the plant population is ideal to optimal, running from 48,000 plants per acre to 54,000 plants per acre. Growers want to be in the 30,000 to 60,000 per acre plant range.

Fusarium Wilt damages  cotton plant.

During the early season, growers are always worried about diseases affecting the young plants. Fusarium Wilt can be troublesome fungal disease. In mild instances, leaves will wilt and drop, leaving bare stems. Plants will die in the worst case. Some areas are dealing with various Fusarium problems. Check out the UC IPM website to read more about Fusarium Wilt.

This is something growers need to monitor. If they suspect potential problem areas, they should consult their pest control advisors. Also, veteran farm advisor Dan Munk of the Fresno County UC Cooperative Extension is a good resource.

Alfalfa harvesters are busy in the field.

On the alfalfa front, growers are well into the second cutting of their crop. Aphids are coming on strong now. Lygus and lygus nymphs are become prominent as well. With grain crops drying, alfalfa is the only lush plant around for these pests to inhabit.

It’s important now for growers to leave a quarter swaths of uncut alfalfa at the end of each field to prevent aphids and lygus from migrating to cotton fields. I suggest leaving 2 percent of the acreage uncut around the border and center of the fields, if there is a neighboring cotton field. 

I want to wish everyone an enjoyable Memorial Day weekend.