How To Battle Insects And Disease In Snap Beans

European corn borer damage

The list of insects and diseases that plague processing snap bean growers in the Northeast and upper Midwest hasn’t changed much over the years. Some of the crop protection options, however, are evolving.

In the area of insects, two that continuously show up in snap beans are the European corn borer (ECB) and the potato leafhopper (PLH). According to Russ Groves, a professor in the department of entomology at the University of Wisconsin, these pests are reasonably easy to control with the products currently available. What researchers are trying to do, he explains, is make some inroads and bring more reduced-risk technology into the mix.

Zeroing In On ECB

ECB overwinters in the upper Midwest and has two generations per year. As its name implies, this insect is principally a pest of sweet corn and field corn, and spends its first generation attacking those particular crops.  

The second generation, however, is what concerns snap bean growers. “ECB can get into peppers and other crops, such as snap beans,” explains Groves. “Females will lay eggs on plants at flowering and pin bean stage of development and those eggs then hatch. They don’t cause a lot of overt damage to the plant or significant yield drag, but they have an unlikable behavior of boring into the pods. So when the processing beans go to the plant, the electronic sorters have a hard time kicking out the corn borer-infested beans. One infested bean in a thousand is sufficient to reject an entire load.”

The industry currently bases the timing of insecticide applications on planting date and when the crop is at a susceptible stage for damage. For late-planted beans, for example, which are put in the ground in early to mid-July, the susceptible stage occurs in early to mid-August, when they are flowering and the adult corn borer moths are flying and laying eggs. “It is at the flowering stage when applications of pyrethroids are made,” he explains. “It is a very definable treatment window.”

Some new control options for ECB, however, are being investigated. Reduced-risk products classified as the anthranilic diamides, which includes DuPont Crop Protection’s Coragen, are currently being looked into as possible seed treatment options in snap beans. “Trials that were conducted in Wisconsin in 2010 showed that both rynaxypyr (e.g. Coragen) and the new cyazypyr (e.g. Verimark), both in the above-mentioned class of chemistry, show promise as future potential seed treatments,” says Groves.
“During the past couple of years, we have been looking at seed treatment and in-furrow applications of these products,” he adds. “They are systemically mobile and will move up into the plant. We are now trying to learn how to position them to use in the snap bean IPM program.”

Targeting PLH

Unlike ECB, PLH overwinters in the south and then makes the trek
northward each year. PLH colonizes potatoes, snap beans, and a number of other commodities.

Offering growers a cultural control method, Groves points out that one way to avoid leafhoppers is to plant early. As the pest has to migrate to Wisconsin, leafhoppers often haven’t made their way to the northern area of the country in time to attack the earliest planted snap bean crop.
Pyrethroids provide good control, but Groves says that about 90% of growers now use an at-plant seed treatment such as Cruiser (thiamethoxam, Syngenta Crop Protection). This seed treatment also helps control another key pest of snap beans, seed maggots.

“We look forward to the future possibility of having a snap bean seed treatment premix that contains both cyazypyr and thiamethoxam. And in this instance, several pests — including ECB, PLH, and seed maggots — would be targeted in one seed treatment,” adds Groves. “This area of investigation remains under way and new control options could be available in just a few years.”

Disease Management

In the area of disease control, a couple of the biggest disease threats growers deal with are root rots and white mold. There are some exceptions to that list, though, says Amanda J. Gevens, professor and Extension plant pathologist in potatoes and vegetables in the University of Wisconsin’s Department of Plant Pathology. In very wet years when foliage remains damp for long periods of time, growers will see more bacterial blight and brown spot.

The root rot complex — which consists of the fungal and fungal-like pathogens aphanomyces, pythium, rhizoctonia, and fusarium — and white mold, however, are issues each year. Root rot problems can be an issue early in the season when there is high soil moisture and cool conditions.
Offering some cultural control tips, Gevens says one way to discourage root rot pathogens from taking over fields is to rotate snap beans with small grain crops and cereals, which are not good hosts for the disease. She also says growers can reduce the risk of root rot problems by planting later in the season, such as in mid to late June or into July.

For growers who need to plant early in the season, Gevens advises them to do a shallow seeding, especially if weather conditions are expected to be cooler with high soil moisture (under 55°F). If high-pressure fields are anticipated, she encourages growers to use seed that is treated with a protectant fungicide.

Limit Moisture, Disease

   Moisture also is conducive to white mold problems. To reduce the instance of this soil-borne disease, Gevens suggests that growers keep the plant canopy as dry as possible.

Increasing between-row spacing and situating rows parallel to prevailing winds will also help reduce moisture levels. Growers must also pay attention to their irrigation schedule and avoid overwatering situations, she adds.
Managing nitrogen late in the season is another way for growers to reduce the incidence of the disease. “Excessive nitrogen will create a denser plant and that can help increase leaf wetness under the canopy, creating a good environment for white mold,” warns Gevens.

Chemical Controls

To successfully keep this disease at bay, growers need to have a foliar management plan in place using specific fungicides with strategically timed applications. Gevens says there is a short list of fungicides (thiophanate methyl and boscalid) that are registered and commonly used in Wisconsin for white mold on snap beans.

 The timing of applications, she says, should be at 30% bloom, and seven days later or at 100% bloom. “If growers spray prior to 30% bloom, they will lose quality of control,” she adds.

That short list of products, however, may be growing in the coming years, says Gevens. New chemistries are in the pipeline for white mold control that are anticipated for registration within the next few years. She mentions the fungicide Fontelis from DuPont Crop Protection, which received registration in March, as one of the controls.

“BASF and Bayer CropScience have submitted registrations for new white mold materials in dry beans, that, in time, may have a place in snap bean
disease control,” she concludes. 

Leave a Reply

Featured Stories
Montmorency tart cherries
Stone FruitWinter Storm Surprises Utah Fruit Growers
April 20, 2015
Snow and cold temperatures threatened tart cherries already in full bloom. Read More
Stone FruitNew Product Developed To Prevent Cherry Cracking
April 20, 2015
Biofilm, developed at Oregon State University, protects fruit from rain-related losses. Read More
FruitsMarch Was The Fifth Warmest Month On Record In Washington
April 20, 2015
Wapato recorded all-time high of 80 degrees. Read More
citrus black spot symptoms
Insect & Disease UpdateCitrus Black Spot Rears Its Ugly Head Again In Southwest Florida
April 20, 2015
Recent confirmed findings of the fungal malady forces USDA-APHIS to expand regulated area. Read More
tomatoes and strawberries
BerriesScientists Seek To Save Flavor Of Tomatoes And Strawberries
April 17, 2015
A $500,000 grant will enable University of Florida researchers to focus on how light can affect the quality and taste of produce after harvest. Read More
GrapesThe Economic Impact Of Grapevine Leafroll Disease
April 17, 2015
Different control strategies are recommended depending on the prevalence of the disease in vineyard blocks. Read More
Natalie Parkell and Kevin Osburn of Vertical Horizon Farms
CitrusSmall Family Farms Can Survive [Opinion]
April 17, 2015
It is reassuring amid the corporate climate the agriculture industry has experienced in more recent times that there is still room for the little guy, and — more importantly — a need. Read More
GrapesTable Grape Commission Awarded More Funding To Study Postharvest Treatment
April 16, 2015
The research will ensure California grape exports continue uninterrupted. Read More
Tom West Blueberries family
BerriesUrban Sprawl Doesn’t Stop 4th-Generation Florida Farm From Growing
April 16, 2015
Growing in town supports the evolution of Tom West Blueberries. Read More
Golden Rice
CitrusMore Social Commentators Changing Their Views On GMO Crops
April 15, 2015
Could public opinion be swayed by evolving narration on genetic modification? Read More
The Latest
Montmorency tart cherries
Stone FruitWinter Storm Surprises Utah Fruit Growers
April 20, 2015
Snow and cold temperatures threatened tart cherries already in full bloom. Read More
Stone FruitNew Product Developed To Prevent Cherry Cracking
April 20, 2015
Biofilm, developed at Oregon State University, protects fruit from rain-related losses. Read More
FruitsMarch Was The Fifth Warmest Month On Record In Washingt…
April 20, 2015
Wapato recorded all-time high of 80 degrees. Read More
citrus black spot symptoms
Insect & Disease UpdateCitrus Black Spot Rears Its Ugly Head Again In Southwes…
April 20, 2015
Recent confirmed findings of the fungal malady forces USDA-APHIS to expand regulated area. Read More
tomatoes and strawberries
BerriesScientists Seek To Save Flavor Of Tomatoes And Strawber…
April 17, 2015
A $500,000 grant will enable University of Florida researchers to focus on how light can affect the quality and taste of produce after harvest. Read More
GrapesThe Economic Impact Of Grapevine Leafroll Disease
April 17, 2015
Different control strategies are recommended depending on the prevalence of the disease in vineyard blocks. Read More
Natalie Parkell and Kevin Osburn of Vertical Horizon Farms
CitrusSmall Family Farms Can Survive [Opinion]
April 17, 2015
It is reassuring amid the corporate climate the agriculture industry has experienced in more recent times that there is still room for the little guy, and — more importantly — a need. Read More
GrapesTable Grape Commission Awarded More Funding To Study Po…
April 16, 2015
The research will ensure California grape exports continue uninterrupted. Read More
Tom West Blueberries family
BerriesUrban Sprawl Doesn’t Stop 4th-Generation Florida …
April 16, 2015
Growing in town supports the evolution of Tom West Blueberries. Read More
Golden Rice
CitrusMore Social Commentators Changing Their Views On GMO Cr…
April 15, 2015
Could public opinion be swayed by evolving narration on genetic modification? Read More
EquipmentTips To Reduce Soil Compaction In The Field
April 15, 2015
Growers are encouraged to check and maintain proper tire pressure as temperature changes throughout the growing season. Read More
FruitsNew Protective Coating Available For Bee Hives
April 14, 2015
Sustainable crop management company Biobest has announced the launch of “Bee-Coat,” a new protective coating for bumblebee hives. It is Read More
Gala green tip apple bloom
Apples & PearsApple Scab Spores Begin To Emerge In Pennsylvania
April 14, 2015
Now is a good time to apply copper sprays to protect trees. Read More
FruitsRecord Low Snowpack In Washington State
April 14, 2015
Experts say snowmelt occurring earlier than expected. Read More
Crop ProtectionMore Help Needed To Track Brown Marmorated Stink Bugs, …
April 14, 2015
This pest, a problem in apples, tomatoes, and other fruit in the North, has recently moved into Georgia.    Read More
NutsPart 2: Spring Weed Management Tips For Almonds: Reduce…
April 14, 2015
Follow these tips to help improve long-term efficacy of herbicides. Read More
NutsPart 2: Combating Navel Orangeworm: IPM Approaches to R…
April 14, 2015
Follow these IPM approaches to reduce unnecessary sprays and manage pyrethroid resistance. Read More
CucurbitsHow To Control Damaging Diseases In Melons
April 14, 2015
Some of the top diseases to watch for include Fusarium wilt, angular leaf spot, and powdery mildew. Read More