Before several well-publicized incidents of illness in the Northwest, California, and Japan, most people gave microbial food contamination little thought. Many different strains of microbes can cause human illness; one of the strains is E. coli, a bacteria normally present in animal intestines, including humans.
Although the majority of strains are harmless, certain others can cause diarrhea, vomiting, stomach cramping, and high fever. A few strains can be fatal and E. coli 0157:H7 is one of those. Gardeners worry that manure of infected animals can contain these dangerous bacteria. Meat products can be well-cooked and remain safely edible. What about the garden lettuce?
If you use fresh manure, there is a small risk that disease pathogens may contaminate the vegetables. The risk is greatest for root crops and leafy vegetables where the edible part touches the soil. To cause infection the vegetable would have to come from a garden where fresh, raw manure was applied, and the manure would have to be from an animal infected with one of the dangerous E. coli strains.
WSU horticulturalists and food specialists suggest these precautions:
Farmers and gardeners have been using manure on vegetables for a very long time. It is an excellent source of organic matter to build soil tilth, and also of many plant nutrients. If you choose to use manure, follow sensible rules and exercise caution. Handled with care, and used fully composted (broken down), it can help us produce abundant quantities of healthful food.
Blight diseases are always most troublesome in cool, wet summers. Sanitation is very important. Immediately get rid of all the dead vines and fruit. The fungus can live in decayed plant refuse in the soil. Do not compost infected plants.
Planning is the next step. You were right to move or rotate the crop. See to it that next year your tomatoes get planted where no tomatoes, potatoes, eggplant or other related crops have been grown for at least two years.
Keep your garden well-weeded. Nightshade, which is a weed in the Solanum family just as tomatoes and potatoes are, and other weeds can carry the disease and spoil your rotation scheme.
Next summer space the transplants far enough from each other so that they can get good ventilation. This will allow them to dry quickly after a rain. Do not wet the foliage when you irrigate. Stick to a staked growing system rather than caging or allowing the plants to sprawl. With this method the plants are pruned to one or two vines which are trained up tall stakes. This system generally produces earlier and bigger fruit as well as less disease. Its disadvantages are that it is more labor intensive and the per-plant production is reduced slightly.
If you do all of this and still have disease, pick off and dispose of the affected plant parts as soon as you notice them. You may decide to apply fixed copper regularly as a preventative fungicide. Because copper is a naturally occurring element, its use is acceptable to many organic gardeners. It is only effective to prevent disease; it cannot cure an infected plant. Be sure to follow label directions and precautions. Other fungicides are also available and registered for use on tomato late blight.
Your carrots may have been infested with the larvae of the carrot rust fly, a common pest in our area. There are several things you can do to minimize or eliminate the problem this year.
First of all, rotate your garden. Consecutive annual planting of carrots in one spot will cause a build-up of the pest. Rust flies usually have three generations each year. Second, you may want to wait to plant your carrots until after the first generation of adults is dying out. Plant in mid-June and grow them under optimal conditions, so they mature quickly. Harvest them before the next rust fly generation can do much harm.
Unfortunately, microclimate, weather, and other factors can vary the time of rust fly emergence, so avoiding the rust fly maggots by specially scheduled plantings is always a risk. A much surer pest control method, which will guarantee worm-free carrots, is the use of floating row covers. In the past gardeners made frames over their carrot beds and covered them with screen or fabric netting. Now we have light-weight materials called floating row covers, which don't require support; the plants themselves hold them up. Sunlight and water can get through the row cover, but the carrot rust fly can't. Floating row covers come under various brand names and are available through garden catalogs and at better garden centers.
When rust flies are screened out of carrot plantings, they can't lay their eggs at the base of the plants. These eggs are the source of the offending maggots that eat through the carrot, leaving rusty brown tunnels.
All the crops you named are heat-lovers. In our area they are best planted in mid-May after the soil has warmed and the weather stabilized. (If you are using cloches, coldframes or rowcovers, you can get them in a couple of weeks earlier.)
Beans are seeded directly into the garden. Most varieties will do well here and they are relatively easy crop to grow.
Zucchini and other squash can be started in the house or directly in the garden. If you are going to grow transplants, sow them 2 weeks before you want to put them out. Squash resent transplanting, so use a large pot (4 inches in diameter) and handle the roots carefully. Be sure to harden them off. Expose them to outdoor conditions during the day and bring them back in at night for at least 4-5 days before planting. The transition from warm indoor temperatures to cool nights can set plants back if they are not hardened off.
Tomatoes are long-season crops, so you must use transplants to get a running start. Choose one of the shortest-season varieties you can find. If started inside they should be planted in mid- to late March. This year you may want to buy transplants. Varieties that produce dependably and have done well in our taste tests include: Early Girl, Champion, and Stupice. Excellent cherry-type varieties are Sweet 100, Sweet Million, Sun Gold, and Yellow Pear.
A plastic cloche will allow slightly earlier planting, but only a week or two at most. The real benefit will be that the extra warmth under the plastic will make the plant grow better and set fruit earlier. Peppers, eggplants, cucumbers and squash also benefit from this kind of protection in spring. For more abut ways to grow heat-loving crops in our cool climate, see Enhancing Heat.
Make sure you are growing a "short season" or "early" variety of tomato. Many of the big, beefsteak types, that are popular elsewhere, will not mature in our area. 'Early Girl,' 'Stupice' and 'IPB' are three reliable, short-season varieties. For more about choosing the right tomato, see Tomato Varieties.
Some gardeners with light, well-drained soils may want to plant on this traditional date. Most of us with typical, heavy, western Washington soils should wait until early to mid-March. The extra time will allow the soil to dry and warm a bit more.
Peas are quite hardy, but they will rot if planted in cold, soggy soil. Last year on February 22nd I took a picture of ducks wading in a big puddle in the middle of a Seattle community garden. With the unusually wet winter we have had so far, a delay will probably be needed again this spring for many of us. For lots more information on growing peas, see All About Peas.
If you don't have time to have a test done, try about 2 pounds (4 cups) of 5:10:10 per 100 square feet or 100 feet of row. In most organic fertilizers the nutrients will not be as concentrated, so you must compensate by using more. I usually mix up my own organic fertilizer. A good recipe is:
4 cups of blood meal (or 7 cups cottonseed meal)
and 4 cups of bone meal
and 4 cups of kelp meal (or 8 cups wood ash)
This recipe makes enough fertilizer for 100 square feet or about four 4-foot by 6-foot beds. For more information on making raised beds, see Soil Preparation and Garden Layout.
Seedlings raised in our homes or greenhouses must be gradually acclimated to the stress of life outdoors. Cold, wind and sun take a little getting used to!
Gardeners usually find a protected spot, where the plants will only get a few hours of morning sun. The transplants are put out after breakfast and taken in before dinner. After about a week of this treatment, they can be planted out if the weather forecast is mild enough for that specific crop. For detailed suggestions on how to handle transplants, see Hardening Off Transplants.
The missing ingredient was almost certainly light. In February and March we get lots of gray, dark weather. Even when the sun shines, the days are pretty short still at our latitude. If you have a south-facing window (unshaded by tall Doug firs) you might just get enough light to do a decent job with transplants. But why gamble? An inexpensive, fluorescent shop light fixture can guarantee sturdy transplants every time. Rig it so that it can be raised and lowered. For more complete information on this subject, see Starting Your Own Transplants.