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Home  > Question of the Week

Question of the Week

Permalink What information can you give me on pest management and fertility for cherry trees?


Answer: I am pleased to provide you with information on cherry tree integrated pest management and fertility.

Please refer to the ATTRA publication Organic Tree Fruit Production. This publication provides a good introduction to the principles of organic tree fruit production. Many of the general principles of organic weed management, soil fertility, and general pest management apply to organic cherry production, so I would encourage you to look at this publication as a resource. This publication also emphasizes that ecological management of the orchard floor can have positive impacts on tree health and pest management. I will address some specific pests for organic cherry production in this letter, however.

Pest Management: Disease

Choosing disease resistant cultivars is a good starting place for minimizing reliance on pesticides. To begin with, sweet cherry varieties are much more susceptible to brown rot and bacterial canker than tart cherries. Some sweet cherry cultivars--Angela, Chinook, and Early Burlat--are resistant to buckskin disease (1), a virus-like disorder which may or may not be a serious disease in your area.

Both powdery mildew and leaf spot can be controlled with regular sprays of sulfur (sulfur is considered "organic" by most certifying organic growers' groups). Bordeaux mix (also considered organic) may be more effective for leaf spot than sulfur.

Brown rot can be a severe problem on sweet cherries if favorable conditions (high heat and humidity) occur. An organic control program for brown rot should probably include the following:

* Encourage air movement with site selection and open pruning.
* Prune out all dead wood and cankers and destroy them.
* Remove mummies--the shriveled, rotted fruit from last season.
* Remove and destroy infected fruit promptly.
* Apply wettable sulfur every 10 to 14 days from petal fall until harvest. Spray more often during wet seasons. Sprays may not be needed in dry seasons or dry climates if the other steps are followed.

Control of brown rot involves the integration of several tactics. Cultural practices and orchard sanitation are the first line of defense. Planting-site selection and pruning are critical to providing sufficient air circulation within the canopy. Good air circulation through the tree facilitates rapid drying of the foliage and flowers after rain or overhead irrigation. Thinning branches to open the center of the tree is a good practice—this can be done in July, as well as during the regular dormant-season pruning. Orchard sanitation practices include pruning and removal of infected twigs and cankers and disposal of dropped, culled, or mummified fruit.

University of California researchers determined that excessive nitrogen fertilization increases fruit susceptibility to brown rot. They also found that pre-harvest sprays of calcium reduced brown rot infection over non-sprayed trees but were not equal to fungicidal control. (3)

Organic growers have traditionally relied on sulfur to control brown rot. The first application of sulfur should be done at the "pink" stage, just before the petals open. This should be repeated at seven-day intervals, especially if rain occurs, for a total of three applications. Two other applications should be made—one at petal drop, the other at sepal drop (usually about 10-14 days after petal drop). The crop is still susceptible to infection later in the season, but treatments during the early "critical" stage will reduce the amount of crop loss without leaving a sulfur residue at harvest. When the weather is hot and dry, the need to spray is not as great.

A promising organic control strategy for brown rot, according to Dr. Michael Glenn at USDA's Appalachian Fruit Research Station in Kearneysville, West Virginia, is to combine sulfur with Surround™ WP Crop Protectant. Derived from processed kaolin clay, Surround is an OMRI- (Organic Materials Review Institute) approved pest control product shown to control or suppress certain insects and diseases. The mechanism by which Surround suppresses powdery mildew, sooty blotch, fly speck, and fire blight (but not scab) in apples. While no studies have been conducted on cherries, I imagine that the response would be quite similar. (6)

Carl Rosato of Woodleaf Farm, Oroville, CA, consulted with ATTRA about his techniques in managing brown rot on his organic peach orchard. He relies primarily on a spray mixture of micronized sulfur + rock dust (e.g., Azomite™). However, for a dynamic foliar spray that provides both nutritive and pest-control benefits, Rosato likes to blend a foliar "brew" for all pre-bloom, bloom, and post-bloom sprays. A common tank mixture (per acre) may include: 6-8 lbs Azomite; 5-15 lbs micronized sulfur; 5 lbs soluble potassium sulfate; 1 lb Solubor™ (boron); 5 lbs kelp; and a yucca extract for a sticker. For the pre-bloom spray, he adds copper specifically for brown rot control. Bloom sprays begin at one-third bloom and proceed every 5-7 days all the way through petal fall, for a total of 3-4 sprays altogether. Post-bloom sprays depend on the weather. When rain or humidity approaches, he religiously applies a brew spray as a prophylactic before weather arrives, again every 5-7 days depending on environmental conditions. Brown rot pressure decreases dramatically when it is hot and dry—around 85-90° F. (7)

Bacterial canker is a serious bacterial disease which affects cherries. Bordeaux mix, or other copper-containing fungicides, will exert some control over bacterial canker. However, this control will probably be imperfect, which points out the importance of taking whatever steps possible in eliminating the predisposing factors to bacterial canker--primarily freeze damage. Whitewashing trunks and avoiding drought stress or nutritional stress (especially as the trees are preparing for dormancy) should help to minimize the risk of freeze damage.


Choice of cherry rootstocks may also have an impact on disease management. The two most commonly used rootstocks are Mahaleb and Mazzard. Mahaleb is susceptible to phythophthora root rot in heavy or poorly drained soils. Mazzard is better suited to heavier soils, but it is susceptible to crown gall and several viruses.

Dwarfing rootstocks are also being evaluated in the US to make cherry production more efficient. Recently some new rootstocks such as Colt and the Gisela series produce fruit trees from standard size down to 45% of normal. These new root stocks are not yet widely tested in B.C. Semi-dwarf cherry trees may be kept at 12 ft high (3.6 meters). At the present time dwarf sweet cherry trees are not as small as dwarf apples. Gisela 5 seems to be the most widely used of the two and is about half the size of Mazzard. It is also more susceptible to pests than Gisela 6, something to consider when using organic production practices (4). Referenced below is a publication that lists the more commonly-used cherry rootstocks and their characteristics. This will help in determining what is best for your farm and preventative strategies in organic production.

Insect Pests

One of the major insect pests of cherry is the cherry fruit fly (Rhagoletis cinulata and R. fausta). Failure to adequately control this pest can cause severe crop loss due to the presence of fruit fly larva (maggots) in the cherries at harvest. Both federal (USDA) regulations and consumers demand a zero tolerance for maggots in fruit at harvest. Regarding insect pests, if you plan to wholesale the fruit, you may have few non-chemical options available to you since cherry processors and wholesalers maintain what amounts to zero tolerance for cherry fruit fly maggots. Recently the use of Spinosad has been quite effective at controlling Cherry Fruit Fly. Spinosad is derived from a naturally-occurring bacteria and it is approved for use as a pesticide in cherry production. It has been used in combination with bait as well as applied as a foliar insecticide. While it has not proven to provide 100% control of Cherry Fruit Fly, it has reduced population numbers significantly. A bait (GF-120NF) is an attractive substance with spinosad as the active ingredient. It is lethal to flies that feed on it while "grazing" on the tree. This bait is "squirted" and spattered on the trees weekly at 20 fluid ounces per acre diluted in about 1.5 to 2 gallons of water per acre. Entrust is a spinosad-based product that kills flies both by contact and residue. It is generally applied by air-blast sprayer every 7-10 days and has had excellent results. (5)

Lastly, for diseases and pests, sanitation is always helpful. Removing and destroying prunings, cutting out disease-infected wood, and roguing out wild plum and cherry trees in the orchard vicinity are all examples of good orchard sanitation practices.

Grower profiles and networking is always very helpful in transitioning to organic. I have listed contact information for an organic cherry grower, Cynthia Lashbrook, under “resources” below. She is also an organic crop advisor and would be an excellent resource for organic cherry production.


1) Stebbins, R. L. and L. Walheim. 1981. Western Fruit, Berries, and Nuts. HPBooks, Los Angeles, CA. p. 96.

2) Hall-Beyer, Bart and Jean Richard. Ecological Fruit Growing in the North, Jean Richard Pub., Trois Rivieres, Quebec, 1983, p. 78.

(3) Hansen, Melissa. 1996. No Magic Bullet Exists for Brown rot Disease Control. The Good Fruit Grower.

(4) Hansen, Melissa. 2006. Growers Worldwide Choose Productive Rootstocks: the perfect cherry rootstock has yet to be found. The Good Fruit Grower. V. 15 No. 10. May 15th, 2006.

(5) Smith, Timothy. (no date). Western Cherry Fruit Fly (Rhagoletis Indifferens Curran) and its Management in The Pacific Northwest United States. Washington State University Tree Fruit Program.

(6) Glenn, D. M., T. van der Zwet, G. J. Puterka, E. Brown, and P. Gundrum. 2001. Efficacy of Kaolin-based particle films to control diseases in apples. Plant Health Progress an online journal. doi : io. 1094/PHP-2001-0823-01-RS.

(7) Peach Brown Rot Control. Organic Farming Foundation Research Report, Grant 92-26. Carl Rosato, Woodleaf Farm, Oroville, CA. Accessed July 2002. (PDF / 3 M)


Stromnes, John. 2006. Bugged to death by flies—Growing organic cherries is tough but getting easier. Western Montana InBusiness Monthly. Vol. 4, No. 7.

Hansen, Melissa. 2006. Growers Worldwide Choose Productive Rootstocks: the perfect cherry rootstock has yet to be found. The Good Fruit Grower. V. 15 No. 10. May 15th, 2006.

Cynthia Lashbrook – PCA and Org. Grower
Four Seasons Agricultural Consulting & Riverdance Farm
12230 Livingston-Cressey Road
Livingston, CA 95334



Permalink Are there standards I must meet to host a farm intern?

New Jersey

Answer: Thank you for requesting information from ATTRA on what qualifications you must meet as a farm intern mentor. You also ask about any state or federal programs and other aspects of having interns work on your farm.

Your state takes a strict view of farm workers as statutory employees. In fact, all states are moving toward a stricter interpretation of federal legislation such as the 1938 Wages and Hours Act. Please see the referenced document adopted this year by the National Association of Insurance Commissioners as guidance for its membership.

This trend has implications for health and accident coverage, workers’ compensation, minimum wage, housing standards, and contractual relationships with farm workers. Please see the enclosed articles that explore some of the issues.

The ATTRA Web site hosts the Western Sustainable Agriculture Research & Education (WSARE) Farm Intern Curriculum. To date, no credentialing system for farm mentors has evolved. Those colleges that accept farm internship experiences for college credit set their own standards and requirements.

The National Center for Appropriate Technology makes no claims of any kind about content, accuracy, suitability, or comprehensiveness of legal information provided in this letter. It is the responsibility of farms to investigate applicability of federal, state, and local laws pertaining to wages and hours or any other legalities or interpretations of federal, state or local legislation.


Boker-Smith, Jen and John. 2008. Farmers and New York State disability benefits insurance: A cautionary tale. Organic Farms, Folks & Foods. Winter. p. 14–15.

Byczynski, Lynn. 1992. Becoming an employer: A primer on federal laws. Growing for Market. May. p. 4, 11.

Byczynski, Lynn. 2007. Are your internships legal? Growing for Market. September. p. 13–15.

Byczynski, Lynn. 2007. Exploring the legal and ethical issues of internships. Growing for Market. October. p. 14–15.

NAIC/IAIABC. 2008. An Overview of Workers’ Compensation Independent Contractor Regulatory Approaches. October 24. 30 p.

O’Brien, Elanor, and Jeff Falen. 2009. One farmer’s intern labor perspective. In Good Tilth (OR). January–February. p. 6, 19, 31. Response to Volheim article.

Volheim, Erin. 2008. Outlawing farming internships. In Good Tilth. July–August. p. 12, 14, 15, 27.



Permalink What information can you give me on drying vegetables, specifically tomatoes?


Answer: Thank you for requesting information from ATTRA on vegetable drying designs and methods (tomatoes). Please refer to the ATTRA publication Food Dehydration Options. This publication covers mid-to-large-scale food dehydration methods for the U.S.

Referenced below is information from Golden Harvest Organics on some low-tech methods for drying tomatoes. Note that for successful sun drying you may need as many as 12 days of continuous hot sunshine (with low humidity) . The referenced research paper on using geothermal energy for tomato drying makes the same point: “Sun drying…is limited to climates with hot sun and dry atmosphere with strong winds. Typical areas with such climates are most of the Mediterranean regions.” In the U.S. Southern California is about the only area where sun drying is feasible. Strict food laws and regulations govern drying of cut vegetables intended for sale to the public.

Inventor Allen Dong (1) is a good source of plans for low-tech food dryers. These plans are best accessed via the Web. Allen makes his inventions freely available to the public without patenting them.;topic=17147.0

The second Web site is a discussion group for small-scale food dehydration.


1)Allen Dong
P.O. Box 413
Venita, OR 97487


Andritsos, N. P. Dalampakis, and N. Kolios. 2003. Use of geothermal energy for tomato drying. GHC Bulletin. March. p. 9–13.

Golden Harvest Organics. 2006. Sun or oven drying tomatoes for storage. 6 p.



Permalink What information can you give me on soil management techniques for my farm?


Answer: I am pleased to provide you with information regarding soil management strategies for your new farm. This letter is outlined to provide you with more details regarding amending a heavy clay soil with compost and green manures (i.e. cover crops). Heavy clay soil responds best to organic matter.

On-Farm Composting:
Composting is certainly a way to reduce off farm inputs on your farm as well as increase the organic matter and the workability of a heavy clay soil. Listed below is an introductory publication on composting manure. It will provide you with some basic tips on how to get started on this process for your farm, including carbon to nitrogen ratios, materials that compost well, placement, etc. I have also referenced the Rodale Institute’s “Making and using compost at The Rodale Institute Farm,” from their web site New Farm. They provide a good on-farm example and recommendations for developing a compost system on your farm, including methods of turning and sources of materials.

Some other useful resources to consider are “The On-Farm Composting Handbook” and the “Field Guide to On-Farm Composting.” These are practical handbooks which present a thorough overview of farm-scale composting and explain how to produce and use it. The information on where and how to obtain these books is listed below under “Further Resources.”

Cover Crops:
Cover cropping is another way to loosen your heavy clay soil and provide organic matter. Cover crops are soil-building crops that are not harvested, but are composted or tilled back into the soil. They can be part of a crop rotation, or can be used to prevent soil erosion and improve fertility. When choosing a cover crop you need to make several considerations. There are many ways to use cover crops in a production cycle:

• as a main crop during the primary growing season. Used as a rotational crop, the cover will exclude production of a cash crop.
• as a companion crop, or living mulch, the cover is planted between the rows of the cash crop—for example pumpkins interplanted with white clover.
• as a 'catch' crop for nutrients, planted after harvest of the main crop or between the rows of the cash crop to reduce leaching of nutrients.
• as an off-season crop grown to protect the soil, usually during the winter when there is no main crop—this is not the case in your farm, of course. This is the most common practice in temperate areas.

Pleas refer to the ATTRA Publication “Overview of Cover Crops and Green Manures.” This publication will help outline some of the cover crops used for the specific purposes that I outline above. The ATTRA publication Sustainable Soil Management will be a helpful resource as well.

A rotation plan used in conjunction with cover cropping and compost is an ideal way for a vegetable farmer to increase fertility and organic matter, while minimizing off farm inputs.

In general, many farmers use the season in which the cash crop is produced as a rotation tool. E.g Spring/ fall crops, winter crops, short season cucurbits, solanaceous crops, etc. Farmers will often plant these “types” of crops in blocks and rotate the entire block each year. E.g. The winter crops of radishes, arugula, lettuce, and beets are planted in block one and rotated to block two next year. This “block” system meshes well with cover cropping, as you can simply have one block in cover crops at any one time. The best way to illustrate this is with some examples. Referenced below is a “real farm” sample of crop rotation sequences for a diversified vegetable farm titled “CEFS Student Farm Upper Field Crop Rotation” from the Center for Environmental Farming Systems at North Carolina State University. They grow several acres of vegetables year-round on their student farm.

I encourage farmers, if they have enough space, to plant one block/ section in cover depending on the season—winter annuals such as oats and peas or rye and vetch, or in the summer, buckwheat, cowpeas, or sudan grass.

Cover crops in annual rotations

In annual cropping systems, cover crops are often chosen to maximize benefits such as biomass and nitrogen production. However, other factors must also be considered. For example, fitting a cover crop into the sequence of a crop rotation can be difficult. Therefore, fast-growing, drought-tolerant cover crops that require minimal management are preferred. Cover crops with fast germination and good seedling vigor are usually chosen because of their ability to compete with weeds. Also, species with the potential to reduce pest populations should be chosen, while those that harbor diseases or arthropod pests of the cash crops should be avoided.

Common cool-season legumes used as cover crops in annual rotations include vetches, winter pea and bell bean. Because clovers and medics grow slower and compete poorly with weeds and require more management (e.g., mowing), they are used less commonly in annual rotations. For similar reasons, cereal grains are usually preferred over other grass species, such as bromes, in annual rotations. Sometimes, however, the annual cereal grains can be used as a “nurse crop” for clovers and medics. They are seeded at the same time and the cereal grains are mowed once or twice. This system gives some shelter to the clovers and helps distribute the seed evenly.

In choosing warm- season cover crops, the ability to perform well with minimal irrigation is often of primary consideration. Legume species in this category include cowpea, hyacinth bean and sunnhemp. Typical grass cover crops for warm conditions include sudangrass and sorghum (1).

Managing Cover Crops Profitably, by Greg Bowman, Christopher Shirley and Craig Cramer describes several rotation and cover crop scenarios for vegetable farms. The Nordell Farm profile is particularly inspiring for many farmers.

It is important to have a sprinkler irrigation system to establish cover crops. If you tend to have droughty summers, establish a drought resistant cover crop such as cowpeas with the spring rains.


(1) Ingels, et al. 1993. Selecting the Right Cover Crop Gives Multiple Benefits. California Agriculture 43 (5):43-48.

Sayre, Laura. 2004. Making and Using Compost at The Rodale Institute Farm. Rodale Institute. The New Farm.

Hopkinson, Tim. 2005. Composting Livestock Manure. Klickitat County Solid Waste Department.

Grover, Joel. 2005. CEFS Student Farm Upper Field Crop Rotation. Center for Ecological Farming Systems. North Carolina State University.

Further Resources:
On-farm Composting Resources:
Rynk, Robert, ed. 1992. On-Farm Composting Handbook, NRAES-54, is available for $25.00 per copy (plus shipping and handling) from NRAES, Cooperative Extension, PO Box 4557, Ithaca, New York 14852-4557 or

Mark Dougherty, ed. 1999. Field Guide to On-Farm Composting. NRAES Publishing. Ithaca, NY.

Cover Crops:
Greg Bowman, Christopher Shirley, Craig Cramer. 1998. Managing Cover Crops Profitably. Sustainable Agriculture Network.
This book distills findings from published studies and on-farm experience into a user-friendly reference tool for farmers and agricultural educators. You will find detailed information on how to select cover crops to fit your farm, and how to manage them to reap multiple benefits.

Magdoff and van Es. 2000. Building Soils for Better Crops. Second ed. Sustainable Agriculture Network. Handbook Series 4.
Sustainable Agriculture Publications
Hills Building, room 10
University of Vermont
Burlington, VT 05405
Call to order: 802-656-0484

Cover Crop Seed Suppliers:
Try a local feed or field crop seed supplier! They often carry many different cover crops.

Fedco Seeds
Organic Growers Supply
PO Box 520, Waterville, ME 04903
(207) 873-7333
Call to get a catalog

Johnny's Selected Seeds
955 Benton Avenue
Winslow, Maine 04901
Toll Free: 877-Johnnys (877-564-6697)

Peaceful Valley Farm Supply
P.O. Box 2209
Grass Valley, CA 95945
To place an order, call toll free at 1-888-784-1722.

Turner Seed Co.
Source of cowpea cover crop seed.
211 County Road 151
Breckenridge, TX 76424-8165
Toll-Free Tel 800.722.8616
Fax Line (254) 559-5024

General Farming info:
Grubinger, Vern. 1999. Sustainable Vegetable Production from Start-Up to Market
Publication number: NRAES-104
Cost: $38.00
Length: 280 pages
ISBN: 0-935817-45-X
Date of Publication: August 1999
Available from: NRAES Cooperative Extension
Phone: (607) 255-7654



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