Cow Fertilizer & Tomato Diseases

Where to Get It

• Cow manure sold by the bag or by the truckload from reputable garden centers and composting facilities are composted in large piles that heat up and kill most insects, pathogens and weed seeds. This compost and organic products containing composted cow manure are ready to use. Fresh manure is available from dairy and cattle farms. Sometimes the manure is in one great pile, making collection easy. Other times, you need to walk the pasture and collect the stuff one plop at a time.

Great Soil, Great Tomatoes

• Composted cow manure releases nutrients slowly throughout the season, providing fairly consistent nutrition. It isn't always rich in soluble nitrogen, however, so supplementation later in the season is sometimes necessary to keep nitrogen-loving tomatoes going until frost. Cow manure improves soil structure by increasing both drainage and water retention. The result is consistent moisture, crucial to the steady growth of tomato plants with plump, crack-free fruit. Beneficial microorganisms in manure break down organic matter in the soil, furthering its soil-building benefits.

Fresh Facts

• Fresh manure often has weed seeds and pathogens. Also, the highly concentrated forms of nutrients in raw manure can over-fertilize plants, which can burn tomato roots, stunt growth and inhibit fruit production. Damaged tomato plants are susceptible to diseases, such as verticillium and fusarium wilts, as well as rust and other fungi. Further, fresh cow manure can harbor pathogens, such as E. coli, that are harmful to people. E. coli affects people when infected soil splashes onto fruits and leafy vegetables. Inadequate hand washing after handling manure can also cause E. coli infection.

Preparing Manure

• Put cow manure on the compost pile, where it will provide the nitrogen necessary for composting. Keep the pile slightly moist and turn it regularly to raise the pile's temperature to 131 degrees Fahrenheit for 15 days, which kills most harmful pathogens. To prepare manure directly in the soil, spread several inches of manure and shredded leaves over the vegetable garden, then turn them under with a shovel or tiller. Do this in late fall or winter, at least three months before you harvest the first vegetables.

Herbicide Warning

• Farm manure sometimes contains residual herbicides from grass and feed grain, which can affect plant growth. Ask your farmer if his cows eat herbicide-treated plants. Conduct a simple test by planting a few beans in potting soil mixed with manure compost. Create a control group using only potting soil. Don't let the two groups sit in the same watering pan. Take care of the seedlings for about three weeks and observe. If the leaves of the test group are disfigured and stunted while those in the control group thrive, it may indicate the presence of herbicides.