Farm Progress

The brown stink bug  reared its ugly head two years ago in cotton in California’s Palo Verde Valley in Riverside County.This year, “We’re seeing 40-44 percent average boll damage from brown stink bug,” says UCCE Riverside County Entomologist Vonny Barlow.The insecticide Bidrin is effective towards pest control but cannot be used in California now due to the lack of a state DPR registration.

September 10, 2015

5 Min Read
<p>Vonny Barlow, UCCE Riverside County entomologist, conducts insecticide efficacy and phermone trials in California&#39;s Palo Verde Valley to learn the best control options against the varocious brown stink bug in cotton. </p>

The California cotton industry continues in survival mode these days with growers facing water reductions from a four-year epic drought, acreage competition from high-value permanent crops, flat fiber prices, and now the devastating brown stink bug (BSB).

The brown stink bug reared its ugly head two years ago in California’s Palo Verde Valley (PVV) in Riverside County in the southern reaches of the state. The cotton pest has also been found just to the south in northern Imperial County.

There are no reports that the boll-destroying insect has reached cotton fields in the San Joaquin Valley.

The brown stink bug is currently found in most cotton-growing states around the country. While the insecticide Bidrin is used in most areas for BSB control, the problem is Bidrin is not registered for use in California.

Chilly welcome

In 2013, the brown stink bug attacked PVV cotton fields with a fury. California cotton leader Roger Isom called the unwelcome BSB a “devastating pest.”

“Some growers that year lost one-half to one-full-bale of cotton per acre due to the brown stink bug,” said Isom, executive director of the California Cotton Ginners and Growers Association (CCGGA).

“We found many cotton bolls lying in the bottom of the furrow with piercing marks on the bolls caused by the pest.”

BSB damage

When pest control advisors first found the pest in the PVV, they immediately contacted University of California Cooperative Extension entomologist Vonny Barlow, Riverside County, who identified the culprit and its damage.

“The brown stink bug inserts its mouthparts through the walls of the cotton boll to extract the juices inside,” Barlow said. “These holes can become a pathway for pathogens to enter the boll. The end result can be boll rot, stained fiber, and yield loss.”

The brown stink bug (Euschistus servus) is a brown-colored pest about half-an-inch long with a checkered edge on the rear and side margins of the body, Barlow says. It looks similar to the consperse stink bug (Euschistus conspersus) yet the consperse bug has spots on its legs – the BSB does not.

BSB has caused unprofitability for many growers this year; making the decision to terminate the crop early to minimize crop losses.

Barlow said, “Some growers have said they’ll cut off the water and harvest what crop they can. This is a big issue in this area.”

Barlow believes the pest entered Riverside County from neighboring Arizona. The two areas are separated only by the Colorado River and the invisible state line.

Back with a vengeance

After a tough first year, the BSB-PVV population was smaller in 2014 and no one really knows why. This year, the pesky bug returned with a vengeance.

“We’re seeing 40-44 percent average boll damage this year from brown stink bug,” Barlow explained.

Besides cotton losses, the pest is an economic nightmare for growers on the input side. Prior to the BSB outbreak, PVV farmers applied 3-4 insecticide applications per season for all cotton pests including whitefly and lygus. Since the BSB outbreak, some growers have sprayed up to 11 times.

These sprays are not economically sustainable.

“If it costs $60 per acre for one insecticide spray then multiply it by 11 times and we’re talking a lot of money. A grower cannot continue to farm this way,” said Barlow.

According to the 2014 Riverside County Agriculture Commissioner’s crop report, Riverside County farmers grew almost 10,000 acres of short staple Upland cotton (almost all Bt), plus 14,000 acres of seed cotton.

Barlow field trials

With BSB now in its third consecutive year of PVV cotton, the CCGGA this year funded two research trials led by Barlow.

The first is a 10-acre pesticide efficacy trial with seven insecticides and-or product combinations at Chaffin Farms in the southern PVV, including the products Bidrin, Acephate, Indigo, and others, plus an untreated control for comparison.

A second trial conducted at Red River Farms focuses on pheromone trapping to follow BSB movement from field margins into the cotton field.

In the end, Barlow and Isom want to halt BSB in its tracks, and keep the pest from spreading in Riverside County and other cotton-growing areas in the state.

Government red tape

According to Isom, Bidrin insecticide is only used in cotton in the U.S., and is viewed by many researchers and growers as the most effective insecticide product for BSB control across the cotton belt.

While Bidrin received a national registration from the federal Environmental Protection Agency (EPA), the product lacks a state registration in California.

To gain the registration for the Golden State, the CCGGA approached the California Department of Pesticide Regulation (DPR) two years ago to obtain a Section 18 emergency use for Bidrin in Riverside, Imperial, and San Bernardino counties.

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DPR instructed CCGGA to file a 24-C special local needs request instead. As part of the process, a full product registration would be required for Bidrin registration in California, the same as the federal EPA requirement, including a field dissipation study.

Isom says dissipation studies have already been conducted in several other states so it should not be required in California. Yet DPR will not accept outside study findings saying that the study must be conducted within California boundaries.

In the out-of-state tests, Isom says Bidrin use was completely safe for people and animals with full product dissipation in about 48 hours.

Until the California registration is gained, Isom says PVV growers must use about twice the amount of other insecticidal products when compared to Bidrin.

AMVAC, which manufactures Bidrin, is working closely with the CCGGA on this issue with DPR.

Industry frustration

“The unavailability of Bidrin use by Riverside County farmers is frustrating,” Isom said. “You can go right across the river into Arizona where Bidrin is allowed but you cannot use it several miles away on the California side of the border.”

He believes the earliest date to receive a California registration for Bidrin would be 2017.

“CCGGA and AMVAC are committed to getting the registration and we will press, press, and press until we get this thing done,” the cotton leader said.

Will BSB spread?

Looking at California cotton statewide, Isom is concerned that the slow registration process could result in the pest moving into other cotton-growing areas of the state.

“This is a distinct possibility. If it made it across the Colorado River then it can make its way to other areas unless we get this insect under control.”

He concluded, “This could be one more nail in cotton’s coffin until this pest is controlled. We have to get this done.”

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