An Ounce of Prevention Pays Big Dividends

Hi everyone. I'm sure most of you agree with me when I say this year has been a lot kinder to us gardeners with its delivery of more even moisture and somewhat cooler temperatures. Did I say more even moisture? Last evening I was at a small gathering of friends for an evening garden walk. It was raining lightly. One member of our group recounted for us how in two nights she had collected way more that three hundred slugs. We did set a record for the most rainfall in over 100 years for the month of June. This issue's column is about vegetable garden health: How to achieve it and maintain it by preventing diseases from getting a foothold. We all know gardening is not a breeze, but like so many other things, a bit of effort can yield great pleasures.

There will be several prongs to the attack. Employing healthy cultural practices and a properly planned crop rotation will form the backbone. I'm sure you will recognize the supporting branches of the overall effort to manage vegetable diseases effectively.

Many vegetable diseases are picked up from the soil. A previous crop might have been infected, and if the following crop is closely related, "bingo", the next crop will be infected by the same disease from the same soil. It is essential to break this cycle. There are some 250 diseases of fruits and vegetable that are soil borne.

Fortunately, for us here in the Northeast, there are far fewer that we need to worry about. The most prevalent soil borne diseases are fungal. Mycologists and virologists have been studying their spread by soil for a long time. Fungi reproduce from microscopic spores. The spores may be in the soil or on residues of diseased plants left in the soil or even in the seed. If you've been afflicted with a particular crop failure and are fairly certain it was a soil borne fungus, the following should be carefully considered.

Soil borne diseases are easily transferred to another garden bed by forgetting their microscopic components travel on your hands, footgear, trowel, hoe, pitchfork, shovel, and minuscule plant residues. Scrupulous sanitation can prevent their spread.

There are more than thirty common food plant families. For our purposes we can restrict ourselves to ten that we grow in our Catskill gardens. The remainders are for special situations. The ten go by the following common family names: beet, sunflower, mustard, gourd, corn, mint, pea, lily, nightshade, and parsley. To suppress a soil borne disease, as well as to disrupt a pest or weed life cycle, plant a crop that is not related botanically to the previously grown crop.

Botanical relatives share many of the same pests. A rotation example: If your cabbage (mustard family) had clubroot, plant beets, Swiss chard, spinach (beet family); or, plant peas, beans, lentils (legume family) in that bed next year. Keep mustard family members out of that bed for at least three years, and with all there is to choose from, aim for five or seven years.

Make every effort to not have a mustard family member even a close neighbor in your garden. I'm often asked, "I have such a small garden. What am I to do?" The only logical answer is to put in another, some distance from the first, or, try container gardening also away from the first using fresh soil.

Another significant procedure toward preventing disease outbreak and spread is building and maintaining the highest quality soil health. Apply well-rotted compost or manure at the end of the season. Plant a cover crop that can be turned under before it goes to seed. You will improve the number of beneficial soil organisms, promote microbial health, increase the organic content and tilth of the soil, and enhance the availability of nutrients. All of these suppress soil borne disease. Leaving the bed in question unplanted next season is of benefit, too.

However, a better solution to kill undesirable soil borne organisms, many weed seeds, and insects intent on spending the winter, as well, is to "solarize" the bed. Solarization is simple. Tarp the bed with clear plastic, sealing the edges with soil, and leave in place for several weeks. The extreme heat will do the trick. Plan on at least four weeks, longer if possible. And, summer months work best, but late summer early fall with lots of sunshine will be just fine. If snow falls, you might sweep the snow off, remove the plastic, and add a healthy layer of well-composted material.

Regular weeding and mulching to suppress weeds can result in harvests that are several hundred times as bountiful as unweeded or neglected gardens. Weeds rob surrounding plants of moisture, nutrients, light and air movement. Weeds also provide a home for, and frequently an alternate host for, insect pests and, yes, soil borne diseases.

The native wild mustard, as well as field and black mustard, is host to many soil pathogens of the entire family. If you enjoy harvesting these edibles, keep them away from your garden. It pays to get rid of them if anywhere near your chosen crop.

If you grow from seed, always try to obtain seed certified free from disease.

Choose seed for plants that have shown in clinical trials to be resistant to as many pests as possible. If you grow from transplants, scrutinize the candidates before you purchase them. Many a garden problem may begin from infested transplants. When there is doubt, put it back. Buy from trusted, reputable dealers. Saving small cents on seedlings may not be worth it.

Water the soil, not the plant. I'm sure you've heard that before. Use a soaker hose, trickle irrigation, or hand water the soil. Splashing water and prolonged leaf wetness favors the development and spread of many diseases. Water deeply less frequently, and your plants will have deeper roots less prone to water stress.

Remember, any stress makes all things more vulnerable to attack. Space your plants to receive maximum sunshine and air drainage. If you haven't a map or notebook on your garden, now is the time to begin one. You should record what you planted when, the date of first harvest, likes and dislikes about the variety, fertilizers used, pest control measures taken. And, over the winter, a new map utilizing you new rotation strategy.

Ask yourself how well your garden soil drains. Is it more heavy clay than not? Consider importing some sandy loam to incorporate. Your plants get their nutrition from the soil you provide. Most of our native soils provide all the minerals our vegetables need for sound development. Well drained soils maximize root function and suppress disease build up. A healthy plant can resist or certainly withstand minor attacks without succumbing. It is never too soon to have a pH test of your soil.

All of our native soils are acidic. Even when well limed, they will eventually return to their acidic state over time. Test at least every three years. You want to aim for a soil pH 6.0 to 6.5. You don't want to raise stressed plants.

Until next time, keep your cool. And if anyone has a recipe using all these slugs, please let me know.


From The Garden of Ed. Submitted for publication in The Towne Crier on August 13, 2003

© 2003 Ed Mues. All Rights Reserved.