Pending approval by the California Department of Pesticide Regulation, the state’s walnut growers will be able use Manzate and Penncozeb to control walnut blight without the need for an emergency use exemption under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) – at least through July 30, 2016. That’s when the supplemental Section 3 label, which United Phosphorus, Inc., received for the two fungicides, expires.
The Section 3 registration, which was announced in August, applies to Manzate Flowable, Manzate Pro-Stick, Manzate Max and Penncozeb 75 DF products.
These labels replace Section 18 emergency exemption registration. For more than 20 years, Section 18 has governed the use in California of Manzate and Manex, a similar product which Manzate replaced in 2010, to control walnut blight. The Section 3 label eliminates the time and expense for the industry to request an emergency use exemption for Manzate each year and the uncertainty each season of receiving approval to use the product.
“That’s great news,” says Northern California walnut grower Dave Keyawa, who is also a member of the California Walnut Board and the California Walnut Commission.
But, it’s not the only favorable development in a season when growers are expected to begin their harvest sooner than usual. Such an early start would reduce the risk of damage to the crop from rain later in the fall.
Growers are also cheering the announcement in July that India has opened its market to U.S. walnuts. Also in July, researchers announced results of a new study which shows that eating a modest amount of walnuts on a regular basis can protect against prostate cancer.
“Both developments should help sustain grower pricing and the movement of increased production,” he says. “It’s very apparent that the growers’ assessments have really paid off, not only in health research but in production research. Next year growers will vote on retaining the California Walnut Board, which is influential in production research and food safety in the walnut industry.”
Assuming growers use the growth regulator, Ethephon, to advance maturity, Keyawa expects this year’s harvest to start around the Sept. 7 in Butte and Glenn counties.
That’s where he and his brother, Ron, grow considerable acreage of walnuts as part of their Keyawa Orchard, Inc., operation. In addition, their Tri Counties Walnut Hulling facilities located in Ord Bend, Calif., has been in operation for more than 30 years.
The walnut handler subjective estimate puts the size of California’s 2013 walnut crop at 494,000 tons. That’s 19,000 tons or about 4 percent smaller than last year’s estimate.
“Two factors that may influence this number will be sunburn damage and the first crop from new plantings,” Dave says. “Either can decrease or increase the final sound nut deliveries. In addition, sunburn can affect kernel quality and color.”
This year’s production challenges for growers have included reduced deliveries of surface water and the continuing need to follow Good Agricultural Practices to ensure a safe, wholesome product and protect California’s reputation for producing some of the world’s highest quality walnuts, Dave notes. Along those same lines, responsible growers have followed voluntary Best Management Practices in the use of pesticides and fertilizers to protect water and soil quality, he adds.
Much of the insect pressure on the walnut orchards in his area this season has come from the usual pests – coddling moth, crown gall, scale and walnut husk fly. Hot summer weather led to spikes in mite numbers, as well, Dave reports. However, another new threat has been popping up in the orchards in the past few years – the walnut twig beetle. Boring into the green wood of walnut trees, it can infect them with the thousand cankers disease fungus, which it carries.
University of California Cooperative Extension farm advisors have reported problems with the disease in other counties. But, Rick Buchner, Extension farm advisor for Tehama County, who also covers walnuts in Butte and Glenn counties, has not heard of any outbreaks of thousand canker disease in his area.
Still, growers here have been dealing with more pressure this season from walnut blight. “Late rains probably contributed to the increase,” Dave says. “Concerns of newer diseases, such as anthracnose, botryosphaeria and phomopsis also are on the rise.”
In this year's early varieties, such as Ashley/Serr, Dave was seeing 40 percent packing tissue brown in the week of Aug. 5. Typically, P.T.B. tends to increase about 10 percent to 20 percent per week. That would have put the crop at 100 percent P.T.B. by August 28th, setting the stage for harvest to begin by the second week of September, if not a day or two sooner.