Rotate Chemistry, Irrigation Methods


Bob Collins
Simplot Grower Solutions
Orland, California

I am a California Pest Control Adviser and fourth-generation farmer in northern California. We grow rice, dairy, corn and alfalfa. While working on the family farm, I received my PCA license and joined Simplot Crop Solutions seven years ago.

Because we had dry weather last year, some rice was planted early, and we continued planting into June. May and June were cool, so both the rice and the weeds had a slow start. We had a hot summer with a lot of heat units, which resulted in average yields, depending on the area you were in. The high heat units also caused some quality issues that seemed to be across the board.

As far as rice acres, I consult in the northern Sacramento Valley from Colusa to Willows. The plant phenology of the weeds appears to be changing, so we are seeing more herbicide resistance. Rotating chemistry and water management methods, along with using correct timing and maintaining the quality of applications are more important than they have been in the past.

Increased Herbicide Resistance
We have three different ways of irrigating rice: Leather’s Method, pinpoint flood and continuous (permanent) flood. So along with rotating effective chemistries, we have to rotate irrigation models to allow us to use different chemistries. For example, we might apply RebelEX® CA herbicide with pinpoint and Leather’s Method, whereas in the permanent flood system, we might apply Butte herbicide.

I started using RebelEX CA — a pre-mix of Clincher® CA and Granite® SC — in an early pinpoint application instead of Butte and the thiobencarb herbicides. As we are seeing changes in the weed phenology and increased resistance, you have to rotate chemistries. I like RebelEX CA because it’s an effective broad spectrum herbicide for both grasses and aquatics, and one jug is easier for the grower to manage than two.

Currently, Butte is a commonly used herbicide, but it doesn’t pick up grasses. In this program, we rotate Granite® GR herbicide and a clomazone product to manage watergrass, which is our biggest culprit. Because the area in which you farm dictates the weed spectrum, the challenges in Willows may be different than the ones in Colusa. You have to be aware of the resistance issues to determine which chemistry to use.

Patience and Diligence Key To Success
During the season, I keep a detailed logbook with chronological notes to keep track of what is going on. Each field has its own page. I can look back from year to year to see if something has changed and where we have had issues or success. This information is very helpful for the upcoming year.

For example, we’re seeing a new, vigorous watergrass coming on later in the season. The problem is it emerges after we have made all our herbicide applications before the plant enters the reproductive stage. We also have regulations for herbicide pre-harvest intervals. When the University of California correctly identifies the species, then we can figure out a control program.

Simplot Grower Solutions is very progressive. They want their PCAs to be knowledgeable and technically sound. During the season, our agronomic support team talks daily and shares experiences about such things as application timing and water management. It’s a cooperative effort.

A lot of good people work in this industry, and California farmers are very good at what they do. We just have to be patient and diligent to manage and thrive no matter what challenges we face.


More about Bob Collins

  • Bachelor’s degree in crop science and horticulture, California State University-Chico.
  • Certified Crop Adviser.
  • Consults on rice, almonds, walnuts, prunes, corn and alfalfa.
  • Has consulted for seven years and farmed his entire life.
  • Member, California Association of Pest Control Advisers; American Society of Agronomy.
  • Son Blaine, 28.
  • Enjoys spending time on the family ranch and golfing.


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