New Insecticides Greatly Improve Grape Insect Management

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The grape berry moth is an annual problem on about 50% of the grape acres around the Great Lakes in New York, Ohio, Pennsylvania and Michigan. Females glue their eggs on the berries and larvae hatch out and feed in the berries. Insecticides have been used for 100 years to control the grape berry moth and reduce the infestation from 24-30% to less than 1%. Until recently, broad-spectrum insecticides with long residuals were used to manage grape berry moth. However, new insecticides have been registered and they provide tremendous opportunities to selectively manage insect pests in grape vineyards.

“The past 10 years has seen a dramatic change in the spectrum of insecticides available for grape producers, with new modes of action and pest spectra allowing an unparalleled opportunity for growers to target specific pests for control while also minimizing the risk to non-target organisms.

There is now increased potential for realizing integrated control, since many of the most effective new insecticides have been evaluated and shown to have relatively low impact on natural enemies. For example, registration of the insect growth regulator insecticides methoxyfenozide and diflubenzuron for use in vineyards and the recent availability of the diamide insecticdes rynaxapyr and flubendiamide allow more selective and long-lasting control of lepidopteran pests without high levels of natural enemy mortality.

Acaricides have also changed from broad-spectrum to more selective chemistries. The vineyard manager now has an array of different acaricide modes of action available, many of which can selectively kill pest mites without injuring predatory species. Some of these are also systemic, thereby providing a route of exposure that further protects predators from direct contact with the acaricide.”

Authors: Isaacs, R., et al.
Affiliation: Department of Entomology, Michigan State University
Title: Vineyard IPM in a changing world: adapting to new pests, tactics, and challenges.
Source: Anthropod Management in Vineyards: Pests, Approaches, and Future Directions. 2012. Springer. Pgs. 475-480.

100 years of Fungicide Protection Against Brown Rot of Stone Fruit

Brown Rot on Peach

Brown Rot on Peach

The brown rot fungus infects all the acres of cherries, peaches and nectarines in the U. S. Ash-gray masses of millions of spores appear on the fruit and the fruit becomes completely rotten and soft within a few days. Brown rot caused substantial fruit losses before the development of fungicides. Most peach growers expected to lose 50-75% of their crop. With the development of a finely-powdered sulfur fungicide about 1912, stone fruit growers began widespread spraying to control brown rot. This spraying has continued to this day.

“Who does not love the delicious taste of fresh peaches, nectarines, plums, apricots, or cherries? Because of their popularity, stone fruits are grown all over the world, but it is not only consumers who like these tasty fruits. Some fungi have specialized in infecting and colonizing stone fruits wherever they are grown. 

There are ways to reduce disease pressure in commercial orchards, including the removal of fruit mummies from the tree canopy, pruning out cankers and removal of wild plums surrounding orchards. However, these measures do not prevent brown rot disease, and growers are still dependent on the application of fungicides for blossom blight and pre- and postharvest disease management.”

Authors: Schnabel, G., et al.
Affiliation: Clemson University.
Title: Sustainable brown rot management of peaches in the southeastern United States.
Source: Outlooks on Pest Management. 2010. October. Pgs. 208-211.

Fungicide Spraying is Critical for African Potato Production

African Potato Fields Fungicide Treated (L) Untreated (R)

African Potato Fields Fungicide Treated (L) Untreated (R)

Potato consumption has increased dramatically in Sub-Saharan Africa in the past ten years as more people have moved to cities and have diversified their diets. Potato production has increased to meet the demand through the planting of more fields with potatoes which are encroaching on forestland. Potato yields remain low in Africa primarily due to damage from the late blight disease. Increasing farmer knowledge about late blight and the importance of fungicide recommendations could dramatically increase potato yields.

“Potato cultivars grown in Uganda have low levels of general resistance to late blight. As such, most commercial potato farmers rely on fungicide applications for control of Phytophthora infestans, the causal agent of late blight.

Potato has become an important staple and cash crop in the highlands of eastern Africa. These areas experience moderate temperatures (about 15–22°C) and receive relatively high amounts of rainfall (>1200 mm per year) that are favourable for potato production. However, these same conditions favour severe epidemics of late blight, and as such, late blight is a major limitation to potato production in high humid elevations.

In Uganda, potato late blight has been a serious problem since the introduction of the crop into the country in the early 1900s… During the 1990s, six varieties with resistance to late blight were released. However, resistance to late blight in these cultivars has since been overcome and significant yield losses experienced. Additionally, susceptible varieties are still greatly desired by farmers due to their good agronomic characteristics. Invariably, fungicides must be used to ensure disease control.”

Authors: Kankwatsa, P., et al.
Affiliation: Department of Crop Science, Makerere University, Uganda.
Title: Efficacy of different fungicide spray schedules for control of potato late blight in Southwestern Uganda.
Source: Crop Protection. 2003. 22:545-552.

Control of Cherry Maggots Has Become Very Difficult in the E.U.

Churry Maggots

Cherry Maggots

Adult cherry maggot flies deposit eggs under the skin of the fruit and the hatched maggots feed inside the berry. There is zero tolerance for maggot-infested cherries in the marketplace and insecticides have been used for over 100 years. However, in the E.U. with increased restrictions on insecticides and lack of newly-registered products, control of cherry maggots has become problematic.

“The European cherry fruit fly, Rhagoletis cerasi L. (Diptera: Tephritidae) is the major insect pest of sweet and tart cherries throughout Europe, infesting up to 90% of fruit in untreated sites. A great need has arisen for effective control techniques because of an almost zero tolerance of infested fruit in the fresh market, notwithstanding an agreed economic threshold of 2% infestation. Cherry fruit fly control in the European Union (EU) has recently become very difficult as a result of programmes to reduce the use of broad-spectrum insecticides, for reasons of environmental and human safety. Such withdrawals of insecticides have occurred in the absence of identified alternatives for R. cerasi. In Germany, its management is currently achieved by the application of systemic insecticides (e.g. acetamiprid, dimethoate), authorized by special permits and, for dimethoate, with many restrictions on use.”

Authors: Bockmann, E., et al.
Affiliation: Institute for Plant Protection in Fruit Crops and Viticulture, Germany.
Title: Bait spray for control of European cherry fruit fly: an appraisal based on semi-field and field studies.
Source: Pest Management Science. 2014. 70:502-509.

High Taxes in the E.U. Will Not Reduce Pesticide Use: Pesticides are Essential

windmills

Dutch Farm

Pesticide use is very high in the E.U. and policies to reduce use have been adopted. Under consideration are taxes on pesticides. Some people believe that pesticides are not essential and that alternatives are available and, as a result, believe that taxes would cause farmers to reduce their use of pesticides. However, recent research in the Netherlands shows that, due to their essential importance, pesticide use is unlikely to go down even with very high taxes. The main effect of high taxes on pesticides would be to reduce farmer income.

“Pesticides are integral components of modern crop production systems. Recently, attention is focused on the use of economic incentives to reduce pesticide use and its related indirect effects. The European Union’s (EU) pesticide policy envisages the use of pesticide tax and levy schemes.

The aim of this study is to assess the effectiveness of different fiscal measures in reducing pesticide use and environmental spillovers by using detailed farm-level data from Dutch arable crop production.

Increasing the tax rate (for both high- and low-toxicity products) to 80% and 120%, total pesticide use is decreased by almost 3% and 4%, respectively. These scenarios show that even high taxes are not able to achieve significant reductions in pesticide use. Moreover, high taxes decrease farm revenues as the 4% pesticide decrease is accompanied by a 22% decrease in farm revenue. Producers’ rigidity in reducing pesticide use, thus avoiding the tax burden, may be attributed to the damage preventing role of pesticides and their capacity to reduce output variability.

The dilemma inherent in pesticide taxation is that the use of pesticides may be so essential for some crops or regions that tax rates would have to be very high to impact pesticide use. This could result in a major reduction in farm income as depicted through the pesticide tax scenarios presented in this work… Results show that even high (and politically challenging) tax rates would result in a small reduction in the use of pesticides due to the rigidity of Dutch farmers in reducing pesticide use.”

Authors: Skevas, T., et al.
Affiliation: Wageningen University
Title: Can economic incentives encourage actual reductions in pesticide use and environmental spillovers?
Source: Agricultural Economics. 2012. 43:267-276.

Herbicide Adoption Contributed Greatly to Increased Corn Production

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Corn yields tripled in the U.S. between the 1930s and 1980s. Many new technologies and practices contributed to this increase in corn yields: hybrids, fertilizers, herbicides, insecticides, increased plant populations, early planting. A researcher at the University of Minnesota studied all of these factors to determine their contribution to the increase and determined that herbicides contributed about ¼ of the increase due to better weed control.

“Corn (Zea mays L.) yields in Minnesota have increased from the 2,010 kg/ha yield level of the pre-1930’s to the current 6,290 kg/ha average. This increased yield can be attributed to a series of technological, cultural, and management practices adopted by farmers. My objective is to attempt an analysis of the magnitude of the changes and the relative contributions to grain yield each practice has made over the 50-year time period.

Improved weed control by the use of herbicides on 93% of the hectarage has increased yields 23%.”

Author: Cardwell, V. B.
Affiliation: University of Minnesota, St. Paul.
Title: Fifty years of Minnesota corn production: sources of yield increase.
Source: Agronomy Journal. 1982. 74[November-December]:984-990.

They’re Back: Cabbage Maggots Reappear Following Insecticide Restrictions

Cabbage maggots

Cabbage maggots

Damage from Cabbage Maggot

Damage from Cabbage Maggot

Cabbage maggots feed on the roots of cole crops (broccoli, cabbage, cauliflower, brussels sprouts). The maggots destroy the roots and the plants wilt. Cabbage maggots were effectively controlled for several decades by applications of organophosphate insecticides. However, recent restrictions on the use of organophosphates have resulted in less effective control and reappearance of cabbage maggots as a severe pest of California cole crops.

“Cabbage maggot is one of the most destructive pests of cruciferous crops in North America and Europe and has become the major persistent pest of cruciferous crops in the central coast of California. The value of cruciferous crops is estimated at 1 billion USD in California. In the Salinas Valley of California, cruciferous crops are grown in more than 34,398 ha and are valued at >$485.5 million USD. The majority of this acreage has been affected by cabbage maggot. Important crops that are at-risk from cabbage maggot include broccoli, cauliflower, cabbage, broccoli raab, and Brussels sprouts.

Cabbage maggot flies lay eggs in the soil around the base of the plant. A single female can lay about 300 eggs under laboratory conditions. Legless, 8-mm long white-maggots feed on the taproot and affect normal plant development. The most common above-ground feeding symptoms of cabbage maggot are yellowing, stunting and slow growth.

Since 2008, regulatory agencies in the state have enforced stringent restrictions to curb the use of organophosphate insecticides in commercial Brassica crop production, leaving growers with limited options to combat cabbage maggot infestation. Because of the fewer effective IPM options, widespread crop losses to cabbage maggot have been reported from 2008 to the present.”

Authors: Joseph, S. V., and J. Martinez.
Affiliation: University of California Cooperative Extension.
Title: Incidence of cabbage maggot (Diptera: Anthomyiidae) infestation and plant damage in seeded Brassica fields in California’s central coast.
Source: Crop Protection. 2014. 62:72-78.

Dangerous Respirable Dust Increased by Organic Farming in California

Airborne Dust From Cultivation

Airborne Dust From Cultivation

Health effects of breathing dust can be major. When inhaled, small dust particles can travel easily to the deep parts of the lungs and may remain there, causing respiratory illness, lung damage, and even premature death in sensitive individuals. People in California are exposed to unhealthful levels of small dust particles more frequently than to any other air pollutant measured. California farmers have minimized dust emissions by using herbicides to reduce weed populations instead of plowing the dry soil.  However, organic farmers do not use herbicides and cultivate their fields which results in significant increases in respirable dust in California.

“Respirable dust (RD), defined as particles smaller than 4µm diameter, was collected at the implement from 29 farming operations performed for furrow-irrigated tomato, corn, and wheat crop production over a 2-year period. …Among the cropping systems studied, those that required more tillage or land preparation to be performed when the soil was driest produced the most RD.

Cultivation of organically managed corn caused the greatest increase in RD, more than four times baseline.

In the organically grown crops, all operations related to soil structure improvement were performed in the dry fall. The organically grown corn was disked five times and land planed only once in the fall, while the organically grown tomatoes had four disking and three land-planing operations. As a result, the organically grown tomatoes had a much higher RD production. As in 1994, the organically grown crops produced more respirable dust than their conventional counterparts. The RD increase relative to conventionally grown crops ranged from 15% for the organically grown corn to 40% for the organically grown tomatoes.”

Authors: Clausnitzer, H., and M. J. Singer.
Affiliations: Department of Land, Air & Water Resources, UC Davis.
Title: Intensive land preparation emits respirable dust.
Source: California Agriculture. 1997. 51[2]:27-30

Increased Insecticide Use Protects Onions from Viral Infections

weeds

Onions infected with iris yellow spot virus

Iris Yellow Spot Virus (IYSV) was first discovered in the U.S.in 1989 infecting onions in the Treasure Valley of Idaho and Oregon. IYSV typically does not kill plants; however the virus reduces plant vigor and bulb size. Once plants are infected with IYSV, there is no cure. The virus is transmitted to onions by the feeding of an insect: onion thrips. The disease spreads rapidly in fields with large numbers of thrips. Losses up to 100% have been reported. Onion thrips populations are reduced by the application of insecticides in onion fields thus preventing transmission of the disease to onion plants.

Iris yellow spot virus pressure in this region has not been nearly as bad as it was last year, when it wiped out some onion fields. “The virus seems to have been held off well this year,” said Paul Skeen, who farms near Nyssa, Ore. Farmers in the Treasure Valley area of southwestern Idaho and eastern Oregon produce about 25 percent of the nation’s bulb onions and the virus is one of their main production challenges. It weakens the plant and reduces onion production. It can substantially reduce onion bulb size, which is important because larger onions fetch a higher price. The disease is spread to onions by thrips, and Skeen said many growers in the area started spraying for thrips earlier this season and they sprayed more often. Skeen started spraying 10 days earlier and sprayed every seven to 10 days as opposed to every 14-20 as he has done in past seasons. “I’ve got a good crop coming because I stayed on top of it. I think everybody’s been doing that,” he said.

While onion growers in the Treasure Valley area typically start their thrip spraying programs around Memorial Day, many started in early May this year, said Stuart Reitz, an OSU cropping systems extension agent in Malheur County. While onion growers in this area normally make about six applications for thrips in a season, many have made eight or nine already this year and a few are up to 10, he said. “That helped keep the thrips population down,” Reitz said.

Author: Ellis, S.
Affiliation: Reporter.
Title: Onion virus pressure not as severe as last year.
Source: Capital Press. August 8, 2014.

Herbicide Use Conserves Water, Tripling Sorghum Yields

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Sorghum Yield: Bushland, Texas

Sorghum is grown primarily in Great Plains states where it is used as a livestock feed. Early grain sorghum production generally involved clean tillage for weed control which eliminated most surface residues. When retained on the surface, crop residues increase soil water storage which increase crop yield. A USDA-ARS laboratory was established in Texas in 1938 and numerous tests have been conducted on ways of increasing sorghum yield in the very dry Texas climate. When herbicides became available and tillage was no longer required for weed control, more residues remained on the soil surface, more water was conserved and sorghum yields increased dramatically.

“In early dryland studies at the USDA laboratories in Bushland, Texas, USA, most residues were plowed under. Residue management for sorghum production received a major boost when improved herbicides and planting equipment became available in the 1960s. Retaining crop residues on the soil surface with no-tillage and improved herbicidal weed control are largely responsible for the increased water conservation achieved since the early 1970s. For 37 studies at the laboratory, preliminary analysis revealed that dryland sorghum grain yields more than tripled from 1939 to 1997. A major increase occurred in the early 1970s when using no-tillage became common. From 1939-1970, mean yield exceeded 2000 kg ha-1 only six times, but exceeded that amount 20 times after 1970.

Soil water content at planting was the dominant factor contributing to yield increases with time. Most increases in soil water content at planting occurred after the early 1970s, when improved herbicides became available and using conservation tillage (crop residue retention on the soil surface) received major emphasis at the laboratory.”

Authors: Unger, P. W., and R. L. Baumhardt.
Affiliation: USDA-ARS.
Title: Crop residue management increases dryland grain sorghum yields in a semiarid region.
Source: Sustaining the Global Farm. Selected Papers from the 10th International Soil Conservation Meeting held May 24-29, 1999. Pgs: 277-282.