Tag Archives: California

Dangerous Respirable Dust Increased by Organic Farming in California

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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

Artichokes (California’s Official Vegetable) Would be Heavily Damaged Without Insecticides

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Artichoke Plume Moth Damage

Artichoke Plume Moth Damage

Artichoke Plume Moth Larvae

Artichoke Plume Moth Larvae

In 2013, artichokes were proclaimed to be California’s official vegetable.99.99% of all commercially-grown artichokes are grown in California. The artichoke is a member of the thistle family and was introduced into California in the mid-1800s where it was met by a native insect that had been feeding on wild thistle plants. The insect quickly adapted and began feeding on artichokes and has become known as the artichoke plume moth. Losses result when they feed on artichoke buds and make them unmarketable due to tunneling in the leaves, borings inside the heads, and a blackening of the heads resulting from feeding and frass exudation. Before the introduction of chemical insecticides in the early 1950s, 50-70% of California’s artichokes were unmarketable because of the moth damage.

“Artichoke plume moth (APM), Platyptilia carduidactyla (riley) (Lepidoptera: Pterophoridae) is the most serious and persistent pest of artichokes in California. If unchecked, 70% of the artichoke buds are rendered unmarketable from worm damage. Insecticides are the most important and sole means currently used for the management of this pest.”

Author: Bari, M. A.
Affiliation: Artichoke Research Association.
Title: A potential alternative in the control of artichoke plume moth.
Source: CAPCA Advisor. 2007. October. Pgs. 58-60.

After a 20 Year “Emergency” California Walnut Growers Can Rest Easy With Full Fungicide Registration

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Walnut Blight Spraying

Walnut Blight Spraying

For 20 years, California walnut growers had to convince the EPA to grant a temporary emergency registration for a fungicide to control annual outbreaks of walnut blight. At the same time, the growers assembled the data necessary to make a full registration possible. After 20 years, the EPA granted the full registration and the walnut growers can rest easy.

“Depending on variety, walnut blight can take a heavy toll on walnut production, particularly when inoculum is high and spring weather is warm and wet.

However, with the federal EPA granting Manzate (flowable or dry flowable formulations) a Section 3 registration last year, walnut growers throughout California now have a reliable option for controlling the disease. For the previous two decades, growers in the state could use this and other ethylene bis-dithio-carbamates (EBDCs) products to treat for walnut blight only in selected counties under a Section 18 (emergency exemption) registration. Applying for Section 18 registration required submitting extensive environmental, health and safety data each year.

The walnut blight bacterium (Xanthomonas arboricola pv juglandis) over-winters in dormant buds primarily under the outer bud scales or cataphylls. When buds break in the spring, cataphylls open and young shoots extend past them. Rain drops spread the disease by splashing bacteria onto any green tissue, infecting them.

The disease appears as black lesions on green tissue. As bacteria spread inside the walnut, they grow toward the center of the nut early in the season, destroying the developing kernel.

In orchards with histories of walnut blight damage, protective treatments at seven to 10-day intervals during prolonged wet springs are necessary for adequate disease control.”

Author: Northcutt, G.
Affiliation: Reporter.
Title: Tips for better control of walnut blight.
Source: Western Farm Press. 2014-04-09. Available: http://westernfarmpress.com/tree-nuts/tips-better-control-walnut-blight

Organic Cotton Acreage Down 99% in California

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The US produces about 1% of the world’s organic cotton with most of the production in low-wage countries such as India and Turkey. In the early 1990s, there was tremendous interest in organic cotton-growing in California and many acres were planted. However, high costs for labor-intensive tasks, especially weeding, resulted in clothing companies turning to the foreign producers.

“Organic cotton production reached its height in the late 1990’s in California’s Central Valley with as much as 20,000 acres being grown. Hundreds of textile companies began using organic cotton in their products. (Hanna Anderson, American Apparel, Norm Thompson, Nike, Patagonia, Mountain Equipment Coop, IKEA, Eddie Bauer, to name a few).

Patagonia and Mountain Equipment Coop fully converted their cotton products to 100% organic. However, by 2000, it soon became apparent that organic cotton produced overseas could be grown at about half the price and so the market for domestic organic all but disappeared, with only about 100 acres of organic cotton being grown in California in 2004, 2005 and 2006.”

Authors: Gibbs, M.
Affiliation: Sustainable Cotton Project of Community Alliance with Family Farmers.
Title: Creating Market Demand For Biologically Based Growing Systems in Cotton.
Source: 2007 Beltwide Cotton Conferences. New Orleans, Louisiana. January 9-12, 2007.

University of California Research Saves the Date Industry

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Mite damage

Mite Damage on Dates

California ranks first in the nation in date production accounting for nearly 100% of all dates produced nationally. Banks grass mite has been a persistent pest of California dates since the early 1900s. Banks grass mite causes direct damage on immature green fruit by puncturing cells and sucking the juices from the surface of the fruit. The skin of infested fruit becomes hard and then cracks and shrivels. A heavy deposit of fine webbing is spun over much of the feeding area. The mites work extensively beneath the webbing. The mite population can double every 35 hours. Banks grass mite traditionally has been controlled by applications of sulfur. Frequent use of sulfur to control mites was effective until the late 1980s. Beginning then growers reported that sulfur was no longer effective and a replacement needed to be found.

“Riverside County is the number one producer of dates in California as well as the nation but successful, economical production is limited by Banks grass mite (BGM), the leading pest of dates in the state…. Dr. Peggy Mauk, UCCE Riverside County, was asked by area growers to find an alternative pesticide for controlling BGM. In one year of testing products she came up with an alternative pesticide, Savey…. After one season of testing, Dr. Mauk was able to get EPA to approve an emergency registration for Savey in California for the following season.

The miticide, sprayed with water once early in the season, gives season-long control. In the first year of its introduction, nearly 50% of the growers used it. Three years later over 90% of growers had traded in their dusting machines for sprayers so that they could use Savey…. Savey not only gives season-long control but is easy on the natural enemies (good bugs) and overall crop quality is ideal.

Albert Keck, Chairman, California Date Commission: “The California date industry has benefited greatly from the attention provided to it by the UCCE. Through the recent efforts of Dr. Peggy Mauk, the industry has successfully combated a devastating mite infestation, which if left unresolved would certainly have led to the demise of the industry.””

Title: Mite devastating date crop is foiled.
Source: University of California Delivers. Available online: http://ucanr.edu/delivers/?impact=145&delivers=1

Exempting Organic Growers from State Spray Program Reduces California Tomato Production

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Stunted Tomatoes

Stunted Tomatoes

Beet Curly Top Virus is a viral disease of tomatoes vectored by the sugarbeet leafhopper. In California, leafhoppers overwinter in the foothills and in the spring they migrate down into tomato fields. Since 1943 the California Department of Agriculture has conducted a spray program targeting the leafhopper in the foothills. This spray program has prevented massive losses in tomato fields. However, in recent years organic farming operations in the foothills have been exempt from the spray program. As a result, large populations of leafhoppers have migrated from the unsprayed organic fields into tomato fields with disastrous results.

“Had California’s 2013 tomato crop not been hit so hard by the Beet curly top virus (BCTV) it could have been a banner year for growers.

Bob Gilbertson, plant pathologist with the University of California, Davis, estimates last year’s tomato crop was reduced by about a million tons because of BCTV, which is vectored by the Beet leafhopper.

Tomato plants with BCTV become stunted and develop curled leaves. Upon closer inspection of the undersides of tomato leaves the veins appear swollen and they turn purple, Gilbertson said. Plants also turn a dull green-to-yellow and the fruit is small and tends to ripen prematurely.

Disease transmission begins early in the season as leafhoppers migrate from the foothills to the agricultural valleys, but can also happen during the growing season.

Adult leafhoppers tend to overwinter in the foothills. In the spring the females lay eggs on the green plants in the foothills and acquire the virus during feeding. As new leafhoppers become adults they then migrate to the valley.

The California Department of Food and Agriculture has a curly top spray program where the state sprays the foothills for the Beet leafhopper.

Tomatoes with curly top symptoms began showing up in late March of last year. Losses were the highest in Fresno, Kern and Kings Counties. Yield losses appeared far beyond the western foothills, and even into San Joaquin County.

Why was it so bad?

Gilbertson suspects a combination of favorable conditions for the leafhopper and hosts for the virus in the foothills.

There are limitations on the spray program, which could have helped leafhopper populations thrive.

“The spray program is being constrained now by certain farmers who want to do organic production in the foothills,” he said.”

Author: Fitchette, T.
Affiliation: Reporter.
Title: Virus slams 2013 California tomato yields.
Source: Western Farm Press. 2014-02-12. Available: http://westernfarmpress.com/vegetables/virus-slams-2013-california-tomato-yields?page=4

Fungicides Keep Lettuce from Turning Slimy

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Lettuce Drop

The fungus causing lettuce drop causes a rot that usually begins on the stem near the soil surface and a water-soaked area appears; it can spread downward until roots decay and can spread upward.  The pathogen rapidly ascends the stalk, killing the leaves in succession until it reaches the heart of the lettuce plant. Layers of collapsed leaves lie flat on the soil surface after infection. Inner leaves are invaded completely by the fungus, which reduces the head to a wet, slimy mass. The entire plant may collapse in less than two days.

“Lettuce drop is one of the most destructive diseases of lettuce and has been reported in all lettuce-growing regions of the world. In the USA, the disease regularly occurs in the two primary lettuce-producing states of Arizona and California. Yield losses vary from 1% to nearly 75% depending on conditions, but under ideal disease conditions an entire field may be lost. The disease is caused by two closely related soilborne fungi, Sclerotinia sclerotiorum (Lib.) de Bary and S. minor Jagger.

Sclerotia of S. sclerotiorum can survive up to seven years and their longevity is affected by location of sclerotia within the soil profile, duration of burial and soil temperature and moisture.

Commercially acceptable cultivars with adequate levels of resistance are not currently available. Thus, current management strategies for lettuce drop rely primarily on fungicides such as iprodione and boscalid.”

Authors: Chitrampalam, P., and B. M. Pryor.
Affiliation: Department of Plant Sciences, University of Arizona, Tucson
Title: Population density and spatial pattern of sclerotia of Sclerotinia sclerotiorum in desert lettuce production fields.
Source: Canadian Journal of Plant Pathology. 2013. 35[4]:494-502 Available: http://www.tandfonline.com/doi/abs/10.1080/07060661.2013.841758#.U35Ck_ldV1Y

No Apple Maggots in Northwest Orchards Thanks to Spraying Outside the Orchards

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Apple Maggots

Apple maggot is a native pest of the eastern United States and Canada. In 1979 it was discovered in Oregon and has since moved into California, Washington, and other Western states. Female apple maggot adults deposit eggs singly under the apple skin. Damage is caused when larvae burrow and feed on apple flesh. Browning of the trails occurs as the apple responds to this injury and bacteria associated with maggots cause fruits to rot internally. No Western commercial apples have been infested with maggots thanks to spraying trees outside the orchards to keep them away.

“The first detection of this species [apple maggot] infesting apples in western North America occurred in the United States in Oregon in 1979; flies were caught in neighboring Washington the following year. However, no commercial apples from central Washington, the major apple growing region in the United States, have been found to be infested by R. pomonella, even though adults were first detected within this region in 1995.  

In Washington, an R. pomonella quarantine is established in 22 counties, including two under partial quarantine.

R. pomonella is widespread and abundant in Washington west of the Cascade Mountain range, but is much less abundant in central and eastern Washington except in Spokane County. It occurs in low numbers on the margins of the apple-growing regions in central Washington in native hawthorns and in even lower numbers in unmanaged roadside and backyard apples.

…In the major apple-producing regions of the Pacific Northwest of the United States, control does not occur at the orchard level but rather outside orchards. There is zero tolerance for infested apples. The probability of R. pomonella being moved in apples from Washington to Canada or Mexico is minimized by an extensive annual fly detection and insecticide spray response program conducted by the WSDA and cooperating county pest control boards. …Similar programs exist in Oregon, Idaho, and California.”

Authors: Yee, W. L., et al.
Affiliation: Agricultural Research Service, United States Department of Agriculture
Title: Status of Rhagoletis (Diptera: Tephritidae) Pests in the NAPPO Countries.
Source: J. Econ. Entomol. 2014. 107[1]:11-28.

Fungicides Prevent Destruction of Pistachio Orchards in California

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Alternaria leaf blight

Alternaria leaf blight

Alternaria late blight infects both leaves and fruit, causing early defoliation, severe brown-black stains on the shells and mold contamination of the shells and kernels. Other damage from Alternaria includes poor flavor and possible mycotoxin contamination. Without fungicide applications, alternaria would reduce California pistachio production by 30-50%.

“Alternaria late blight (ALB), caused by Alternaria alternata, A. tenuissima, and A. arborescens, is now considered the most destructive disease of pistachio in California. The disease affects foliage and fruit and is an annual production concern for pistachio growers. On foliage, it can be recognized by the development of large necrotic lesions, and multiple, expanding lesions eventually consume the whole leaf. The lesions are black in the center due to the production of many spores and are surrounded by a chlorotic halo. Under optimal conditions for the disease, the fungus can defoliate a tree in late summer and autumn. On fruit, it is characterized by small necrotic lesions surrounded by a red halo. These are located on the hull of immature nuts. When the nuts develop, one or two lesions can penetrate and decay the hull, resulting in shell staining of the nut underneath. The staining of the shell and colonization of the kernel result in a reduction of the nut quality. Although cultural practices such as irrigation management and pruning to increase air movement and decrease air humidity in the orchard can help reduce ALB, the use of multiple fungicide applications is essential to achieve adequate disease control.”

Authors: Avenot, H. F., et al.
Affiliation: Department of Plant Pathology, UC-Davis.
Title: Sensitivities of Baseline Isolates and Boscalid-Resistant Mutants of Alternaria alternata from Pistachio to Fluopyram, Penthiopyrad, and Fluxapyroxad.
Source: Plant Disease. 2014. 98[2]:197-198.

Herbicides Help to Control Nematodes in Orchards

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Nematode Damage

Nematode Damage (R)

Prior to the 1950s farmers of orchard crops in California had plenty of new land available as an alternative to replanting land that had previously been in production. However, with growing population and increased land values, a greater proportion of fruit and nut production has been on land where older orchards have been removed. Farmers frequently encounter growth problems when they replant. In severe situations, new plants die. Plant parasitic nematodes that are present on old roots are a common cause of the replant problem.

“Orchard removal and site preparation for walnuts can be extensive and expensive, but worth the time and expense to get new plantings off to the best start, according to Joe Connell, University of California Cooperative Extension farm advisor for Butte County.

Nematodes are a main concern, and the first thing that a grower should do is collect a soil sample from the feeder roots in the old orchard and have a nematode analysis done, Connell said.

After the soil testing, the next step is to cut down the trees, and then treat the stump with a herbicide, Connell said. Treating the stumps kills the entire root system, and it will kill out the nematode population that is attached to that root system, he added.”

Author: Coatney, K.
Affiliation: Reporter
Title: Walnut site preparation is essential for healthy orchards.
Source: Ag Alert. January 30, 2013.