Although the 2012 San Joaquin Valley cotton growing season has been virtually trouble free to this point, there are a couple of issues that are not far off the radar.
One is Race 4 fusarium. The other is the growing problem of glyphosate-resistant weeds.
University of California Extension Cotton Specialist Bob Hutmacher says Race 4 fusarium evidence was not as widespread this season as many expected, although new areas did appear.
Steve Wright, University of California Cooperative Extension farm advisor for Kings and Tulare counties said glyphosate-resistant Palmer amaranth and junglerice are spreading. Unless growers taking them seriously and change weed control tactics, the problems will only grow.
Palmer amaranth resistance has become a huge issue in the Mid-South where growers have turned back to cultivation along with alternative herbicides and hooded sprayers to get it under control. SJV growers can expect the same thing to happen unless they take action now.
Hutmacher says fusarium may not have been as evident early as expected, it never goes away, if a field is infected. Under the proper conditions it can return with a vengeance and continue spreading. “Fusarium does not go away,” Hutmacher.
It has evolved into one of the most serious threat to the San Joaquin Valley cotton. If it spreads far enough in a field, it can preclude that field from ever being planted to cotton again. That has already occurred in the valley.
(For more, see: SJV cotton crop cutting out with heavy boll load)
Hutmacher attributes the lack of fusarium evidence to ideal early season growing conditions. When conditions are ideal for seedling diseases, fusarium will also appear. Cotton grew off well this season with little disease pressure.
Secondly, growers planted later in many areas and cotton is less susceptible the later it is planted.
“Later planting is a recommendation in Australia to lessen the impact of the fusarium there,” said Hutmacher.
Pima and Acala are both susceptible to fusarium. Fortunately, there are Pima varieties resistant to it and growers are relying on them where they suspect fusarium lurks. There are no highly resistant Acalas.
Late planting long-season Pima was not a popular option for many growers since April 15 once was the drop dead recommended cutoff date for getting Pima in the ground in time to pick it ahead of fall rains.
Hutmacher says growers have widened that planting window by tweaking in-season plant growth regulator applications and irrigation management. “Growers are now saying April 25 may be alright and if their backs are against the wall, the first week of May may work because growers have learned how to make it work.”
“It is nice to not having fusarium rearing its ugly head quite as much,” Hutmacher says.
Wright likened what he has been seeing with glyphosate-resistant palmer amaranth to the situation in the Mid-South, especially in cotton right after Roundup Ready corn.
He encouraged growers to rogue fields of resistant Palmer amaranth or the problem will come home to roost permanently.
The weed junglerice is demonstrating resistance, particularly in Roundup Ready corn.
Both of these are growing and serious issues for field crop growers.
“We are starting to see these resistant weeds on roadsides and ditch banks. They will creep into fields from there,” he adds.
Wright encourages growers to use alternatives and not be complacent with a good herbicide technology like glyphosate resistance.