Sign up for the
Weekly Harvest Newsletter!

Published every Wednesday, the Weekly Harvest e-newsletter is a free Web digest of sustainable agriculture news, resources, events and funding opportunities gleaned from the Internet. See past issues of the Weekly Harvest.
Sign up here

Sign up for the Weekly Harvest Newsletter

What Is Sustainable Agriculture?

Master Publication List

Search Our Databases

Urban Agriculture

Energy Alternatives

Beginning Farmer

Field Crops

Horticultural Crops

Livestock & Pasture

Value-Added Food Products

Local Food Systems

Food Safety

Marketing, Business & Risk Management

Organic Farming

Pest Management

Soils & Compost

Water Management

Ecological Fisheries and Ocean Farming

Other Resources

Sign Up for The Dirt E-News

Home Page

Contribute to NCAT


Newsletter sign up button

· Privacy Policy · Newsletter Archives

RSS Icon XML Feeds

RSS 2.0: Events, Breaking News, Funding Opportunities Atom: Events, Breaking News, Funding Opportunities


NCAT strives to make our information available to everyone who needs it. If you are a limited-access or low-income farmer and find that one of our publications is just not in your budget, please call 800-346-9140.


How are we doing?


Home  > Question of the Week

Question of the Week

Permalink How can I prevent thistles in alfalfa?

Answer: The presence of weeds in an established forage crop or pasture is usually a sign of a management problem. Fertility, proper planting procedure, and harvest management are the most effective ways to maintain dense, productive pastures. Ensure adequate soil fertility and optimum pH with nitrogen-fixing legumes and applications of lime if your soil test indicates a need.

When establishing new pastures, ensure that you use weed-free seed on a well-prepared seedbed, or use a no-till drill at the appropriate time. Also, be sure to practice good harvest management, whether grazing or haying, by leaving enough forage standing after harvest to allow for regrowth. It is especially important to rest pasture plants after grazing to allow full regrowth, thereby ensuring plant health and productivity.

Consider the following for establishing a weed-free forage crop:

• Control weeds prior to planting with successive tillage. This allows weeds to germinate, which can be killed by the next tillage. Some growers use a broad spectrum herbicide to control weeds prior to planting.
• Apply lime and fertilizers according to soil test, and incorporate with tillage.
• Prepare a good seedbed, with no large soil clumps.
• Select weed-free certified seed.
• Plant with a drill, or broadcast at a higher seeding rate and drag the field with a harrow to obtain seed to soil contact. Good seed to soil contact ensures good germination and seedling growth.
• If weeds occur in the stand, mow them high. Grasses have their growing points at the base of the plant prior to flowering, and weeds like thistles have their growing points higher on the plants. Mowing creates an environment that favors grass growth over weed growth, given proper fertility management.

To learn more, check out the ATTRA publication Thistle Control Alternatives, available at This publication focuses on the cultural, biological, organic, and least-toxic methods available for two of the more troublesome thistles (Canada and musk), with some coverage of other thistles such as plumeless, Italian, bull, and yellow star.

Additionally, since thistles are a widespread problem, most Extension offices around the country have guidelines on thistle control and management. Check with your local Extension office for their recommendations.

Send feedback » Permalink


Permalink When propagating strawberries, do transplants or seeds need be certified organic in order to be certified organic when they are in full production?

Answer: According to language in the USDA-NOP regulation 205.202: "the producer must use organically grown seeds, annual seedlings, and planting stock. The producer may use untreated nonorganic seeds and planting stock when equivalent organic varieties are not commercially available. Seed and planting stock treated with substances that appear on the National List may be used when an organically produced or untreated variety is not commercially available. Planting stock used to produce a perennial crop may be sold as organically produced planting stock after it has been maintained under a system of organic management for at least 1 year. Seeds, annual seedlings, and planting stock treated with prohibited substances may be used to produce an organic crop when the application of the substance is a requirement of Federal or State phytosanitary regulations."

First, if you're growing your plants in a perennial system (multi-year, as in the "matted row" system) and, therefore, won't be harvesting fruit for roughly a year after you plant, you should have no problem getting your fruit certified. Again, the regulation reads: "Planting stock used to produce a perennial crop may be sold as organically produced planting stock after it has been maintained under a system of organic management for at least 1 year."

However, if you are growing the fruit in an annual production system, you may need to purchase organically certified strawberries. Here's the problem: there are organically certified strawberry plants available, but they are very expensive and sold in very small lots. See and

Again, part of the regulation reads, "The producer may use untreated nonorganic seeds and planting stock when equivalent organic varieties are not commercially available." You should be able to convince your local certifier that what is available online is not "equivalent." You might also be able to make the case that organically-certified strawberry transplants at the exorbitant prices listed at Mountain Valley Growers and Backyard Berry Plants are not really "commercial." Rather, such prices would have to be considered as something only for non-commercial backyard hobby growers.

So, in conclusion, if you're using one of the perennial growing systems where you won't be fruiting plants until they've been grown organically by you for at least one year, you can use non-certified plants. Otherwise, you'll have to convince your certifier that the available plants are not "equivalent" or not "commercial."

For more information about growing strawberries organically, see the ATTRA publication Strawberries: Organic Production at This publication provides an overview of organic strawberry production methods. It also covers integrated pest management and weed control techniques that can reduce pesticide use in strawberry production. Included are discussions of weeds, pests, diseases, greenhouse production, plasticulture, fertility, economics, and marketing.

Send feedback » Permalink


Permalink Can I use cardboard and newspaper as mulch on my organic farm?

Answer: Materials that are used to produce and handle organic crops under the USDA's National Organic Program (NOP) must be selected for compliance and used in the context of organic principles for farming and handling practices. For more information, see the ATTRA publication Organic Materials Compliance at Among other information, this publication discusses three basic steps to ensure that materials use is compliant with organic standards and certification.

Regarding the use of newspaper and cardboard, both can be useful materials used in organic crop production for suppressing weeds, retaining moisture and adding organic matter to your soil. NOP regulations allow the use of newspaper or other recycled paper as an "allowed synthetic" with the provision that it be "without glossy or colored inks" (refer to NOP regulations 205.2, 205.601(b)(2), and 205.601(c)). It does take some work to separate out the newspapers that are neither glossy nor use colored inks. Also, there are fruit, vegetable, and meat cartons that are water- or grease-resistant and therefore coated with other types of materials, such as waxes, or impregnated with fungicides. These would also be prohibited for use in organic production.

ATTRA has not found any research studies to establish the impact of black ink used in the printing on newspaper, or whether the inks and glues used in cardboard are completely safe. However, there is abundant anecdotal and experiential evidence that suggests the use of brown cardboard as mulch is very effective as a weed barrier and that it biodegrades and does not appear to pose any substantial threat to the health of the soil and soil organisms. Many organic gardeners and farmers and ecological landscapers use cardboard often and say that it makes great sheet mulch.

A few years ago, ATTRA did research on the different substances that go into making cardboard, as well as the glues, inks, and coatings that may be used. Based on the information available then, the basic components of corrugated cardboard seemed to be relatively benign. Brown corrugated cardboard appears to be the least processed paper product. It therefore would have the lowest number and smallest quantity of chemical substances, compared to white, glossy, highly printed, waxed or otherwise coated cardboard, paperboard, and papers.

If you want to remove some of the variable of other unknown substances used in their production, avoid white cardboard (these may require the use of bleach), waxed boxes, paperboard (such as cereal boxes), and any material with colored ink (may contain heavy metals of other substances) or glossy coatings. There is an abundant supply of relatively plain (minimally printed), brown corrugated cardboard that can be obtained for free in most areas of the United States. Using this, many people can fulfill their mulching needs without the use of riskier materials.

Send feedback » Permalink


Permalink Will baking soda control peach diseases?

Answer: There are at least two baking soda products that are registered with the Organic Materials Review Institute (OMRI) as "certified organic"—Milstop™ and Green Light™. Milstop is aptly named because it is used primarily for mildew control in cherries and other susceptible crops. But it apparently has little or no efficacy against brown rot and here are two reasons:

1) Baking soda is very water soluble, so if you get any rain big enough to cause water to run off the leaf, the baking soda is washed off.

2) The etiology of the disease is such that the first symptoms are often not obvious until many days, even weeks, after the infection. The initial infection might take place even during bloom, but the most common time is during early fruit development. During this time, spores are spread by wind and rain (if you have any) but also by insects that are feeding on the fruit. It might be a plum curculio or a stink bug, but any number of insects can spread the disease. Then, the disease remains more or less quiescent until the sugars begin to develop in the ripening fruit—that is when the brown rot really becomes visible. It's a very common observation of backyard growers to pick an apparently edible peach in the afternoon, leave it on the kitchen counter overnight, and discover a half-rotted peach in the morning.

For more information, see the ATTRA publication Peaches: Organic and Low-Spray Production at Among other information, this publication describes the major diseases and insect pests of peaches and discusses organic or least-toxic control options for each.

If you could keep baking soda on the leaves and fruit, you might be able to combat this disease a little with baking soda, but ATTRA is not aware of any scientific literature suggesting this is true. Even the organic fungicide that does work against brown rot, sulfur, must be reapplied after every rain. It's a pretty good bet to say that brown rot can't be controlled with baking soda, but it never hurts to conduct a little experiment. If you don't want to experiment, stick with sulfur.

It is worth mentioning that there is at least one other fungal disease that has been effectively controlled with baking soda, and that is sooty blotch of apples. The point is that baking soda has been researched for effectiveness in controlling fungal diseases of fruit, and the only two diseases that it is very good at controlling is powdery mildew (of cherry, apple, peach, etc.) and sooty blotch of apples. Again, as always, it's not hard to conduct a little side experiment of your own to see if baking soda might work against brown rot in your particular situation.

Finally, the Chinese and others are using plastic-covered high tunnels to produce organic peaches. Keeping any and all rainfall off the fruit is an almost perfect control—the insects can still spread it, but the fungus, Monolinia fructicola, needs free water in order to germinate. Similarly, the bagged fruit option discussed in ATTRA's peach publication protects the fruit from infection, though the labor might be prohibitively expensive. Research is being conducted at Rutgers in New Jersey.

Send feedback » Permalink


Question of the Week Archives