Grape Mealybug Control in California Depends on Insecticides

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Four species of mealybug feed on grapes in California. They suck out plant content and excrete unused plant material. The result is a layer of sticky, wet honeydew on which thick, black, sooty mold grows. The strict quality standards set by the grape industry and demanded by consumers have led to a dependence on insecticides for controlling mealybug populations.

“Although more vineyards are becoming infested, populations within infested areas are declining because the judicious use of insecticides has successfully lowered mealybug populations in areas that are infested.”

“Season-long control programs for vine mealybug are typically comprised of a combination of insecticide treatments assisted by biological control. … Promoting parasites is very important because they are active late in the growing season and can reduce vine mealybug populations before the pest begins to move to the lower part of the trunk after harvest [where they are protected from insecticides].”

Authors: Chuck Ingels, David Haviland and Steve Quashnick*
Affiliation: UC Cooperative Extension and *Wilbur Ellis
Title: Vine mealybug management in wine grapes in the northern San Joaquin Valley.
Publication: CAPCA Adviser (2012) April:34-37.

Modern Fungicides Continue Control of Potato Disease

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The disease of potatoes known as ‘early blight’ occurs earlier in the season than the well-known ‘late blight’ disease. Early blight is a significant problem in Wisconsin and Minnesota potato fields. Fungicides have been used for over 100 years to protect potatoes from early blight. Recent research in Wisconsin shows that modern fungicides continue to be most effective with newer chemistries expected to continue effective control into the future.

“Potato early blight is a perennial and potentially destructive disease caused by the fungus Alternaria solani. Appropriately-timed, effective fungicides are necessary to limit yield and quality loss. In 2010, we evaluated 38 fungicide programs for early blight control at the University of Wisconsin Hancock Agricultural Research Station on ‘Russet Burbank.’ Programs included an untreated control, conventional and organic grower standard programs, and newer chemistries.”

“The highest yielding program was the Wisconsin conventional grower standard. Organic treatments were ineffective. Several newer chemistries and modified standard programs were effective. At this time, and in the registration pipeline, there are excellent fungicides for the control of potato early blight that will contribute to good fungicide resistance management practices.”

Authors: Kenneth Cleveland, Jamie Dobbs, Rosemary Clark and Amanda Gevens
Affiliation: University of Wisconsin-Madison, Dept. of Plant Pathology
Title: Evaluating the efficacy of fungicide programs for the control of potato early blight in the Central Sands of Wisconsin.
Publication: American Journal of Potato Research (2012) 89:32.

Chinese Ginger Relies on Soil Fumigation

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Ginger, a root crop, is exposed to attack by soil-borne pathogens, nematodes, insects and weed competition. Chinese farmers produce 300,000 tons (FAO) of this important worldwide spice annually from fields that are fumigated prior to planting. A recent experiment showed that the fumigation with methyl bromide doubled ginger yields…

“Ginger weight per category and total weight were significantly affected by the fumigation programs. In the experiment, the highest yield of extra-large fruit (8.6 t/ha) was obtained in the MeBr treatment, while the lowest was achieved in the non-treated control (3.5 t/ha). … A similar trend was observed for total marketable fruit yield, where the highest yield (76.4 t/ha) was produced in the MeBr treatment plots; [while the lowest yield (48.2 t/ha) was achieved in the control plots].”

Authors: Kang Qiao†, Yukun Zhu†, Hongyan Wang‡, Xiaoxue Ji*, Kaiyun Wang†
Affiliation: †Shandong Agricultural University, ‡Shangdong Academy of Agricultural Sciences, *Plant Protection and Inspection Station of Feicheng
Title: Effects of 1,3-dichloropropene as a methyl bromide alternative for management of nematode, soil-borne disease, and weed in ginger (Zingiber officinale) crops in China.
Publication: Crop Protection (2012) 32:71-75.

Herbicide Use Can Increase Bumblebee Populations

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Bumblebees play a crucial role in crop and wildflower pollination. One way to increase bumblebee populations would be to increase the number of wildflowers growing in grassy strips around crop fields. Recent research in the UK has shown that by sowing wildflowers around crop fields where grasses have been suppressed with herbicides, bumblebee populations increase.

“The benefit of applying graminicide [herbicide targeting grasses] was confirmed by a significant increase in sown wildflower cover. This supports previous work showing that graminicide applications can reduce levels of competitive grasses and promote the development of wildflowers.”

“This study has demonstrated that wildflowers can be successfully introduced into existing grass buffer strips when managed with a combination of cultivation, seed and graminicide, producing greater bumblebee abundances than existing conventionally managed strips.”

Authors: Robin J. Blake et al.
Affiliation: Center for Agri-Environmental Research, University of Reading, UK
Title: Enhancing habitat to help the plight of the bumblebee.
Publication: Pest Management Science (2011) 67:377-379.

Consumer Expectations for High Quality Lettuce Require Insecticide Use

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Fresh market lettuce production in the desert growing areas of Southern California and Arizona is a billion dollar industry and the region annually produces >95% of the leafy vegetables consumed in the U.S. in the fall and winter months. Consumers desire lettuce without any blemishes or insect damage. Consumer standards result in the annual use of insecticides on the lettuce crop as described by Arizona entomologists John Palumbo and Steve Castle…

“In desert vegetable production systems, growers have been delivering high-quality safe produce to the fresh market for decades, and this has been accomplished almost exclusively through the use of insecticides.”

“…western lettuce growers and consultants have reported that chemical control is the only effective IPM tactic available for the control of most major insect pests. Naturally occurring biotic control agents are simply not capable of providing the level of crop protection necessary for meeting the marketing demands for fresh produce. … Because of the short time these crops are in the field, minor feeding activity may render the product unmarketable because of high consumer standards.”

“More recently, the fresh produce industry has experienced significant growth in the value-added market, where lettuce and other leafy greens are prepared and sold as fresh-cut lettuce packs and ready-to-eat, bagged salad mixes. The growth of this industry has also resulted in higher cosmetic standards for leafy vegetable crops, often to the point where virtually no insect contaminants or feeding blemishes are tolerated.”

Authors: John C. Palumbo and Steve J. Castle
Affiliation: University of Arizona Department of Entomology
Title: IPM for fresh-market lettuce production in the desert southwest: the produce paradox
Publication: Pest Management Science (2009) 65:1311-1320.

Fungicide Use on UK Crop Acres Results in Significant Reductions in Greenhouse Gas Emissions

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Fungicides are used on more than 90% of the cereal acres in the UK resulting in yield increases of 16-20%. Without fungicide use, it would be necessary to bring about 20% more land into cereal production to meet demand. All of the operations needed to bring a parcel of land into crop production (tractor operations, fertilization, pesticide application) result in the emission of greenhouse gases. Since fungicide use reduces the number of acres that need to be in production, their use is credited with a significant reduction in greenhouse gas emissions.

“The GHG emissions produced by growing arable crops derive mainly from agricultural inputs, such as fertiliser applications, the use of field machinery and crop treatments including disease control measures such as fungicides. … Nevertheless, the largest contributors to barley emissions are fertilisers, which account for 71-76% of all emissions. … Field operations contributed 19-23% of total emissions. … Crop protection chemicals contributed less than 1% of the total emissions.”

“Fungicides were applied to 98 and 87% by area of UK winter and spring barley, respectively, in 2008. … If fungicide treatment had not been applied, an additional crop area of 165,000 ha (17%) on average would have been required each year to produce the same harvested yields of winter and spring barley in 2005-2009. Furthermore, an additional crop area of 638,000 ha (16%) on average would have been required to produce the same harvested yields of the four crops winter barley, spring barley, winter wheat and winter oilseed rape in 2005-2009.”

“Fungicide treatment of the major UK arable crops is estimated to have directly decreased UK GHG emissions by over 1.5 Mt CO2 eq. in 2009. … These results suggest that disease control in UK arable crops can have the positive environmental effect of reducing direct GHG emissions by making more efficient use of the inputs to agricultural production. …use of fungicides applied to control disease in UK barley contributed relatively little to GHGs while increasing yield and decreasing GHG emissions per tonne of crop.”

Authors: David Hughes et al.
Affiliation: Rothamsted Research, Harpenden, Herts, UK
Title: Effects of disease control by fungicides on greenhouse gas emissions by UK arable crop production.
Publication: Pest Management Science. 2011. 67:1082-1092.

Fungicides May Increase Health Benefits of Fruit Juice

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Fungicides are widely-used to control diseases of fruit. Some fungicides have been shown to alter antioxidant metabolism in plant tissues. UK researchers conducted an experiment to see if fungicide applications could increase the health benefits of blackcurrant juice, a fruit grown widely in Europe and New Zealand…

“[Blackcurrant] is well regarded and strongly marketed for its exceptional antioxidant capacity. …cultivars have not yet been released with complete resistance to a range of yield- and quality-reducing fungal diseases. These diseases therefore still require extensive chemical control within plantations. … Fungal diseases in blackcurrant have been demonstrated to be effectively controlled by a range of fungicide classes including the strobilurin group. … In addition to their antifungal activities, the strobilurin group of fungicides have been shown to modulate plant physiology and biochemistry, resulting in yield increases and improvements in crop quality.”

“The impact of fungicide treatment on fungal infection and blackcurrant juice quality was examined in a series of field experiments over the course of 2 years. … In conclusion, the work presented here demonstrates a clear benefit of fungicide application in the control of foliar disease. Furthermore, there is an indication that fungicide application could improve juice quality with respect to both sensory characteristics and potential health benefits of juice consumption.”

Authors: AJ Nwankno, SL Gordon, SR Verrall, RM Brennan and RD Hancock
Affiliation: The James Hutton Institute, Dundee, UK
Title: Treatment with fungicides influences phytochemical quality of blackcurrant juice
Publication: Annals of Applied Biology 2012 160:86-96.

Fungicides Prevent Wheat Losses in the Pacific Northwest – Organic Growers Can Only Pray

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Cool, wet weather causes explosions of the stripe rust fungus in wheat fields of the Pacific Northwest. Two articles by Matthew Weaver explain how most growers applied fungicides to prevent yield loss in 2011 while organic growers could only hope that they would not be hit by the disease.

From “Researchers say vigilance against stripe rust a must”:

“Even though there’s more stripe rust in Pacific Northwest wheat fields this year, researchers say the outlook is good -— as long as farmers spray their fields and keep an eye on them.”

“…most growers in Oregon are already on their second application of fungicide and many will make a third application, which is extremely unusual.”

“In most fields, the stripe rust is under control if sprayed. Very few fields haven’t been sprayed, Chen said. Farmers who haven’t should compare the cost of spraying to the potential for yield losses if they don’t, Chen [research plant pathologist with USDA’s ARS] said. ‘It can not only cause a problem in their fields, but also to their neighbors and potentially to the whole region,’ he said, noting rust spores can be carried by the wind.”

From “Rust resistance key to organic wheat survival”:

“Organic wheat growers in the Pacific Northwest are concerned about stripe rust, an epidemic for which they have few treatment options. … Oregon State University wheat breader Mike Flowers said most organic growers were hit by the stripe rust ‘pretty hard’ but losses vary depending on the variety of wheat they grew. … Corvallis, Ore., farmer Clinton Lindsey, farm manager of A2R Farms, said one of his best red wheat fields was ‘completely devastated’ by the rust.”

“There aren’t many options available to organic producers, researchers and farmers say. ‘Pray or not pray,’ said Owen Jorgensen, a Coulee City, Wash., farmer who is on the northern edge of the stripe rust region.” 

Author: Matthew Weaver
Titles:”Researchers say vigilance against stripe rust a must” 27 May, 2011 and “Rust resistance key to organic wheat survival” 8 July, 2011
Publication: Capitol Press

Crop Breeding Failure Led to Increase in Fungicides in CA Spinach Fields

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The breeding of crop varieties that are resistant to pest organisms is often touted as an effective means of replacing pesticide use. And yet, pest organisms mutate and overcome the plant’s resistance. According to the California Department of Pesticide Regulation, fungicide use in California spinach fields has doubled in the last decade. The reason for the increase has been the breakdown of the plant’s resistance to mildew (Peronospora farinosa f. sp. spinaciae).

“Downy mildew disease is the most important disease problem facing the extensive spinach industry in California. … While downy mildew has been around California spinach fields for decades, the last few years have seen the development of four or five new races. Each new race potentially overcomes the resistance factors in the cultivars being planted at that time, leaving the crop susceptible to severe damage.”

“Integrated management steps must be used. … Resistant cultivars will remain a foundational piece of such a program. Judicious use of effective fungicides will remain important.”

Authors: Steven Koike and Jim Correll
Affiliation: University of California and University of Arkansas, respectively
Title: Spinach Downy Mildew: Outlining the Challenges.
Publication: Crop Notes (University of California Cooperative Extension)

Research Shows Importance of Insecticides for Sweet Potato

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North Carolina is the country’s largest sweet potato producing state, totaling nearly half the entire production in the U.S. Wireworms, which live in the soil and feed on sweet potato roots, are the #1 insect enemy of sweet potato growers. Mark Abney, North Carolina State University entomologist, explains what his research has determined about the value of insecticide treatments for wireworm control…

“Abney was part of the multi-state project that ran from 2004-2007 and was designed to document which insects were major pests of sweet potatoes and begin the process of developing comprehensive IPM programs to best manage these pests. … ‘So, growers who don’t treat with an insecticide for wireworm control on sweet potatoes should expect 40 percent or more of their crop to be damaged by wireworms and for 17-20 percent of the crop to be unmarketable,’ he adds.”

Author: Roy Roberson
Title: Wireworm management a must in North Carolina sweet potatoes.
Publication: Southeast Farm Press. 2012. January 11.