Deadly Biological Parasite of Citrus Pest Can’t Take the Heat of the San Joaquin Valley

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Citricola Scale Damage

Citricola Scale Damage

Certain scale insect species feed by sucking juices from citrus trees. Each mature citricola scale produces more than 1000 eggs which hatch into crawlers that settle on the trees. A severe infestation may reduce tree vigor, kill twigs and reduce flowering and fruit set. In southern California, citricola scale is not a problem because they are parasitized by a wasp that lays its eggs in the scale bodies. The wasp eggs hatch and the tiny wasps consume the insides of the scale. However, these deadly parasites are not effective in the San Joaquin Valley where 70% of California’s oranges are grown.

“Citricola scale is a voracious pest that in high numbers can dramatically reduce yield. A typical Valencia orange tree can produce 325 oranges per tree. If there are 10 citricola scale per twig, yields can drop by 70 fruit per tree, a yield loss of more than 20 percent.

The only effective control method in the valley is insecticide treatments. The parasitic wasp that is an effective biological control in Southern California citrus does not control the pest in the valley because of the high populations of scale produced under hotter valley conditions.

Oil will control citricola scale for organic growers, but it may take two applications per season. There is a list of registered foliar and systemic compounds on the UC IPM website.”

Author: Cline, H.
Affiliation: Western Farm Press
Title: Citricola scale valley’s No. 1 citrus pest
Source: Western Farm Press. Friday, 2012-09-28. Available at: http://www.westernfarmpress.com/orchard-crops/citricola-scale-valley-s-no-1-citrus-pest

A floating Fungus Would Destroy Much of the World’s Rice Crop Without Fungicide Sprays

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Rice Field With Sheath Blight

Rice Field With Sheath Blight

Sheath blight is a disease of rice plants which is caused by a fungus that lives in the soil. When rice fields are flooded, the fungus floats to the top of the water and contacts rice plants; the fungus grows out and moves into the rice leaf. The fungus spreads across the water to adjacent plants. The fungus grows across touching plant parts. The flow of water and nutrients in the rice plant is interrupted and the leaf dies, reducing rice yield. Development of resistant cultivars has been slow, because resistance is linked to undesirable traits such as tall plant stature, late maturity, and poor milling quality. Research has shown that a single application of a fungicide provides almost season-long control of sheath blight.

“Sheath blight of rice, caused by the fungus Rhizoctonia solani, is an economically important rice disease that is occurring throughout the rice-producing areas in the world, including the southern United States. Significant losses in grain quality and yield may occur in severely infected rice fields. Despite its economic importance, there are no completely resistant rice cultivars against this fungal rice disease and control methods for sheath blight are limited to heavy usage of fungicides.”

Authors: Shrestha, B. K., et al.
Affiliation: Louisiana State University Agricultural Center, Baton Rouge
Title: Suppression of sheath blight development in rice and sclerotia germination of Rhizoctonia solani by rice-associated strains of Bacillus spp.
Source: Phytopathology. 2013. 103(Supplement 1)(5):S1.9

Downy mildew of Basil is here to Stay

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Downy Mildew Close-up

Downy Mildew Close-up

Downy Mildew Spore Growth on Basil Leaves

Downy Mildew Spore Growth on Basil Leaves

Downy mildew of basil is a new destructive disease that appears to be here to stay. In the first years of its appearance in the U.S., complete crop losses occurred for some growers because basil leaves with any mildew are unmarketable. Applying fungicides frequently and starting before first symptoms are considered necessary to control basil downy mildew effectively.

“Sweet basil (Ocimum basilicum L., Fam. Lamaiaceae) is the most commercially important annual culinary herb crop grown in the United States. Sweet basil is grown for culinary use for both fresh and dry consumption and as a source of essential oil and oleoresin for manufacturing perfumes, food flavors, and aromatherapy products.

Basil downy mildew… is a new disease of basil in the United States. …In the United States, the pathogen was first discovered in Florida in the fall of 2007. Since that time, basil downy mildew has been found throughout the eastern United States and in regions of commercial basil production in the Midwest and California.

Once basil plants become infected and develop symptoms, they are no longer marketable as a fresh product. …Currently, there is no known resistance or tolerance to basil downy mildew leaving 100% of the sweet basil acreage in the eastern United States vulnerable to the pathogen. Without adequate chemical control options and genetic resistance, basil downy mildew has the potential to destroy basil production in the eastern United States and in all other areas where basil is being produced.

Selection criteria such as foliar morphology, plant architecture as well as the presence of secondary metabolites and other factors that provide a less favorable microenvironment to the pathogen need to be examined as potential avenues for developing downy mildew-resistant sweet basil cultivars. Until this can be achieved, basil growers will have to rely on multiple applications of the few commercial fungicides currently registered to produce a marketable crop. Additionally, for organic basil growers, control of basil downy mildew will be even more challenging because there are fewer approved products labeled for organic use.”

Authors: Wyenandt, C. A., et al.
Affiliation: Department of Plant Biology and Pathology, Rutgers University
Title: Susceptibility of basil cultivars and breeding lines to downy mildew (Peronospora belbahrii)
Source: HortScience. 2010. 45(9):1416-1419.

Pesticide Sprays Improve Food Safety

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Cherry Fruit Fly

Cherry Fruit Fly

Plants are living, dynamic organisms that must defend themselves from bacteria, fungi and insects. Plants in nature synthesize toxic chemicals in large amounts as a primary defense against hordes of bacterial, fungal, and insect predators. Plants respond to attacks by increasing their production of self-defense chemistries. To be effective, these self-defense chemistries are often potent toxicants. The good news is that the levels of natural toxicants of food plants are very much under human control through the application of small amounts of man-made pesticides. Farmers treat crops with pesticides to reduce damage from insects and fungi. When plants do not have to fight off insects and fungi, the plants make less of the self-defense chemicals. Adding a tiny amount of synthetic pesticide reduces exposure to larger amounts of plant-produced toxic chemicals.

“An unrecognized benefit of use of crop protection chemicals is a reduced net exposure to toxicants. …crops that are stressed by competition from weeds, and from attack from infections and bugs, have increased levels of ‘natural’ pesticides. Crops protected from stress have smaller amounts of ‘natural’ pesticide. These ‘natural’ pesticides commonly are mutagenic and carcinogenic, as well as having the capability of inducing a large variety of other types of toxicities. Manufactured crop-protection chemicals are screened for mutagenicity, carcinogenicity, organ toxicity and the like, and exposure is rigorously regulated. Hence, proper use of crop-protection chemicals can cause a net reduction in toxicant exposure by reducing exposure to the potentially more hazardous and abundant ‘natural’ pesticides.”

Author: Mattsson, J. L.
Affiliation: Health and Environmental Sciences, The Dow Chemical Co.
Title: Let’s end the double standard for natural versus manufactured chemicals
Source: J Occup Health. 1996. 38:94-96.

To Increase Income and Competiveness, Public Policy Should Educate African Maize Farmers About the Benefits of Using Herbicides

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Weedy Maize Field: Africa

Weedy Maize Field: Africa

Maize consumption is a major source of calories for millions of people in Sub-Saharan Africa. Within the next few decades, the majority of people in Sub-Saharan Africa will be living in cities. Countries in eastern and southern Africa are increasing imports of staple foods, including maize. In order to be competitive, African farmers need to reduce the cost of producing a unit of maize. Herbicide adoption would greatly reduce costs of growing maize and lead to greater yields and farmer income and competiveness.

“Rural smallholder production remains highly labor-intensive. On average, family labor accounts for 62% of the total cost of maize production in Zambia’s small- and medium-scale farm sector. Promoting the identification and adoption of practices and technologies that save labor and/or identifying labor-productivity-enhancing technologies through research and development will therefore help to make Zambian maize more competitive and allow farmers to maintain profitability even at lower producer prices.

Although only 3% of fields had herbicides applied, regression results suggest the benefits of its use are quite high. All else equal, applying herbicides increases gross margin between ZMK 363,700 to ZMK 376,300 per hectare planted… The magnitude of this effect is fairly large compared to the national average margin of ZMK 1,108,542 (in other words, at the mean, herbicide use would increase gross margins by roughly a third). …these results indicate that public policy measure should be considered to educate farmers about the benefits of herbicide application, as its contribution to smallholder income growth and regional competitiveness may be comparable to and highly synergistic with increased fertilizer use.”

Authors: Burke, W. J., et al.
Affiliation: Zambia Food Security Research Project (FSRP)
Title: The cost of maize production by smallholder farmers in Zambia
Source: Food Security Research Project. Working Paper 50. March 2011. Available at: http://www.aec.msu.edu/agecon/fs2/zambia/index.htm 

Organic Cocoa Growers Likely to Switch to Conventional Production if Financing of Inputs is Made Available

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Weedy Cocoa: Ghana

Weeding Cocoa: Ghana

There are very few certified organic cocoa growers in Africa. The risks of trying to grow an organic crop are great. Many of these growers choose to grow organically because they lack financial resources to purchase inputs including pesticides. With financing of inputs, many of the current organic growers are likely to switch to use of conventional methods with pesticides due to greater yields, income and less risk.

“…the total market share of organically grown cocoa is still relatively very small and accounted for less than 0.5% of the total production in 2002 to 2005.

For producers who cannot afford inorganic inputs and who currently grow organic cocoa, there is a large amount of risk (both in price and in yield) involved with an estimated 30% lower yield compared with conventional (inorganic) production.

The obvious challenge for producers to produce conventionally is to obtain credit up front to purchase inorganic inputs. Given the advent of organizations like the Cocoa Abrabopa Association (CAA) established in 1998 in Ghana, credit is becoming more accessible to producers.

The current organic producers, who are constrained to do so because of a lack of microfinance opportunities to buy conventional inputs (fertilizer, fungicide, etc.), would probably switch to conventional if financing for said inputs became available, say through a microfinance program. Thus, an unintended impact of a microfinance program might be to lead to lower levels of current organic production.”

Authors: Mahrizal, L., et al.
Affiliations: Department of Agricultural Economics and Agribusiness, University of Arkansas
Title: Necessary price premiums to incentivize Ghanaian organic cocoa production: a phased, orchard management approach
Source: HortScience 47(11)1617-1624. 2012.

Herbicide Use on Cotton Farms Could Greatly Increase Income of Farm Families in Africa

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African Cotton Herbicide Experiment

African Cotton Herbicide Experiment

The income of family farms growing cotton in Africa is low largely due to the small size of farms- about one hectare. A major reason that farm size is small is because fields are weeded by hand and there usually is not enough family labor to weed more than one hectare. With use of herbicides, the need for labor is reduced dramatically and individual cotton farms would be able to significantly increase their acreage and incomes.

“Under rainfed agricultural production, common throughout most of Africa, labor bottlenecks at planting and weeding times often critically constrain farm output. During the four to six week period following the first rains, farmers must prepare their soil, plant and conduct the critical first weeding.

Under these circumstances, early season labor constraints, particularly during the first weeding, set an upper bound on the cropped area a family can manage using only household labor. For the average farm household in central Zambia, with five family members, peak-season labor bottlenecks limit the area they can cultivate under conventional hand hoe tillage to about 1 hectare.

In Zambia, herbicide application, instead of weeding with a hand hoe, cuts peak season labor requirements in half.

When combined with dry season land preparation, this reduction in peak season labor requirements enables farm households to crop 2.7 hectares of land under hand hoe cultivation using only household labor. As a result, hand hoe farmers can increase their income from these three crops to 2.9 million Kwacha ($620) per year, triple what they can earn under conventional hand hoe agriculture…

This suggests that cotton company inclusion and financing of one round of herbicides in their cotton packs could potentially raise cotton production and household income considerably.”

Authors: Steven Haggblade and Christina Plerhoples
Affiliations: Department of Agricultural Food and Resource Economics at Michigan State University
Title: Productivity impact of conservation farming on smallholder cotton farmers in Zambia
Source: Food Security Research Project. Working Paper 47. July 2010. Available at: http://www.aec.msu.edu/agecon/fs2/zambia/index.htm 

Fungal Colonies on Apples are not Acceptable to Consumers

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Sotty Apple

 

Sooty blotch and flyspeck are diseases of apples which result from fungi colonizing the fruit surface without penetrating below the peel. These fungal colonies simply grow on the surface of the apple. However, consumers don’t want to purchase apples with any blemishes. As a result, numerous fungicide sprays are used to prevent the fungal colonies and meet consumer demands.

“Sooty blotch and flyspeck (SBFS) is a disease caused by a complex of saprophytic fungi that colonize the epicuticular wax layer of apple and several other fruit crops in humid production regions worldwide. In the eastern half of the continental United States, SBFS is a major problem for commercial apple growers because the dark blemishes of SBFS colonies result in downgrading fruit from fresh-market to processing use, with economic losses as high as 90%

To suppress SBFS and fruit rots, most apple growers in this region apply fungicide sprays every 1 to 2 weeks from 7 to 10 days after petal fall until shortly before harvest.”

Authors: Diaz Arias, M.M., et al.
Affiliation: Department of Plant Pathology, Iowa State University
Title: Diversity and Biogeography of Sooty Blotch and Flyspeck Fungi on Apple in the Eastern and Midwestern United States.
Source: Phytopathology. 2010. 100(4):345-355.

Ebenezer Scrooge Returns as an Organic Ag Advocate

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Ebenezer Scrooge

Ebenezer Scrooge

Hand Weeding

Hand Weeding

Dickens’ fictional character Ebenezer Scrooge believed that young people should work. By not working, he considered the unemployed as “surplus population.” Organic farms require more labor particularly for jobs such as weeding fields by hand since herbicides are not used. Recently, an organic ag advocate in the UK invoked the name of Ebenezer Scrooge to explain how organic ag could make use of the current “surplus population” by putting the unemployed to work in the organic fields.

“Yet if Britain practiced Enlightened Agriculture based on small, mixed, quasi-organic farms we could easily be self-reliant in food. We could also employ all of the three million who are now unemployed, including or perhaps especially the one million unemployed under-25s, in jobs far better than the shelf-stacking and mail-order cold-calling that are now on offer. Instead we produce only about half our food while politicians wring their hands over what Ebenezer Scrooge in a remarkably similar economy called “the surplus population” who alas are left on the sidelines.”

Author: Colin Tudge
Affiliation: Writer
Title: Enlightened agriculture a people’s takeover of the food supply
Source: Food Ethics. Summer 2012. Volume 7; Issue 2. Available at: www.foodethicscouncil.org

California Alfalfa Production Would be One Million Tons Lower with Conversion to Organic Practices

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Alfalfa Weevil on Damaged Leaf

Alfalfa Weevil on Damaged Leaf

California is the #1 dairy state in the U.S. and one million acres of alfalfa are grown in the state. Alfalfa growers use herbicides to control weeds and insecticides to control key pests-the Egyptian and alfalfa weevils. Organic alfalfa growers do not have effective methods of controlling weeds and insect pests and they incur yield losses – particularly by harvesting early to avoid damage. A recent economic analysis from the University of California estimated that organic production of alfalfa is one ton less per acre which would mean a loss of one million tons of alfalfa if the entire state converted to organic practices.

“The Egyptian and alfalfa weevils are the most serious pests of alfalfa, causing yield and quality losses to the first harvest in late winter/early spring.

Most organic growers rely on early harvest to minimize weevil damage, but yields will be reduced.

The risks associated with the production of organic alfalfa hay should not be minimized. Weather and other risks are a continual concern for conventional growers, but organic growers face additional risks such as pest outbreaks that cannot be adequately controlled with organic methods.

Average annual yields in California range from 5.0 to 10 tons per acre with three to ten cuttings depending on location and alfalfa variety. Eight tons per acre over seven cuttings per year is common in the Central Valley. The crop in this study is assumed to yield 7.0 tons of hay per acre because yields of organic alfalfa are often slightly lower than conventional due to only partial control of many pests and weeds and the difficulty meeting the nutritional needs of alfalfa using solely organic sources.”

Authors: Rachael F. Long, et al.
Affiliation: US Cooperative Extension Farm Advisor, Yolo, Solano & Sacramento Counties
Title: Sample costs to establish and produce organic alfalfa hay California 2013
Source: University of California Cooperative Extension. 2013.