Friday, April 27, 2012

Bees, Butterflies, and Pesticides

Evidence is mounting that widespread use of supposedly "safe" chemical pesticides may lie at the root of the problems currently being experienced by beekeepers. One report can be found here. The study mentioned in this report found that feeding bees artificial nectar spiked with the neonicotinid insecticide imidocloprid in tiny amounts resulted in bee behavior like that associated with colony collapse disorder. While the maker of the insecticide, Bayer, debunks the study, I cannot help but wonder if we are ingesting this pesticide any time we consume a product containing high fructose corn syrup (HFCS). Traces of imidocloprid can be found in commercial HFCS, according to the author of the study.

Neonicotinid pesticides mimic the nicotine found in tobacco, a natural pesticide that affects a great many types of insects. Nicotine is particularly effective against the caterpillars of moths and butterflies, several of which feed on tobacco, tomatoes, potatoes and related crops. An anecdote from my garden a few years ago serves to demonstrate how effective nicotine is. During one particularly bad season for tomatoes, we inadvertently allowed a number of flowering tobacco plants (Nicotiana sylvestris) to grow too near the tomato patch. The sweet scented blooms of the tobacco attracted hornworm moths that laid eggs on both the tobacco and the tomatoes. The caterpillars started munching both types of plants, but those on the tobacco became stunted and died when they were about and inch and a half long, too small to do severe damage to the foliage. Those on the tomatoes, however, thrived, growing much larger and doing considerable damage before we could discover and remove them by hand.

One wonders, therefore, if the severe decline in butterfly abundance, observable to anyone who takes an interest in butterflies from one year to the next, might also be a result of chemicals in the environment. A decade old report found, for example, that pollen from corn genetically engineered to contain a pest-killing substance was harmful to monarch butterflies. How many other products that are commonly applied to lawns, flowerbeds and farms contribute similar effects? No one knows. But everyone agrees that butterfly populations are declining, and last March, this report appeared, suggesting that glyphosate, the active ingredient in herbicides such as Roundup, is seriously affecting monarchs and is turning up in humans, too.

There are a limited number of circumstances under which a home gardener might have to resort to chemical pesticide use. Situations involving noxious weeds already established on the property and ineracdicable by hand cultivation can be handled by spot treatment with glyphosate or triclopyr. Otherwise, I cannot think of a good excuse to use either herbicide.

I can think of NO circumstance under which I would resort to a chemical insecticide, with the possible exception of a termite infestation of my house. And then I would have the treatment done by a professional. In the garden, we have learned that proper husbandry and integrated pest management techniques suffice to protect our vegetable crops, and we only grow ornamental plants that are typically pest-free in our region when properly sited and maintained. Many of our plants are native to the southern Appalachians and have natural resistance to pests and disease.

All home gardeners should follow similar guidelines. Chemical pesticides are both expensive and harmful to wildlife.

Wednesday, April 18, 2012

Coldframe Pros and Cons

I'll say up front that we love our walk-in coldframes. Winter gardening will just never be the same again. But in our Tennessee Valley climate, especially with the unusually warm weather in March, they do have one big drawback. They get much too warm for good results with brassicas. We have tried various methods to produce spring crops of broccoli, cauliflower and cabbage without having to resort to almost daily sprayings with Dipel to keep the cabbage butterfly larvae from ruining the crop. We were hoping that the coldframes, which physically prevent the butterfly from reaching the plants to lay its eggs, were the answer. Alas, no. Even with all the windows open, the temperature climbs into the upper 80s on sunny days. We may get some decent cabbage, but broccoli and cauliflower would not tolerate the heat.

So instead of brassicas, we have planted some early beans, and we will soon be replacing the cabbage with squash and cucumbers. We plan to try some fall-planted brassicas, so the plants will be maturing during cooler weather in November and December. In the meantime, we may figure out some way to ventilate the coldframes better, while still screening out the cabbage butterfly. Stay tuned.

Recycle Beer Cartons as Weed Blocker
If you are planning on building a new raised bed and wondering how to deal with existing sod or weeds, you may have considered placing a weed blocker fabric over the undesired plant material. This works great, and you can build a bed right on top, but there is a free alternative: beer cartons. Those trapezoidal twelve-packs that bottled beer comes in make great weed blocker. Separate the cardboard at the glue seams and fold the container out flat. You will see that the flattened cardboard pieces can be interlocked, owing to the way they are die cut. A single layer of these interlocked pieces stops even tough weeds like poke and dandelions. It takes about 18 months for the cardboard to break down, which is plenty of time to eliminate all the weeds under the raised bed. Weedblock fabric, by contrast, does not break down at all. And it does not come packaged with a frosty beverage.

Local Food Report
The first local strawberries have appeared in the market. The ones at Three Rivers Market came from the Colvin Family Farm in Spring City, TN. They must have been forced in a greenhouse, but they are far tastier than the berries now coming in from Florida and California. Good work, Colvin Family! Several varieties of lettuce, along with beautiful rainbow colored Swiss chard, from Hines Valley Farm in Loudon County were also on offer. Watercress from Hancock County appeared to have been foraged. Wild watercress is better than cultivated, in our view, and the harvest of wild watercress is certainly not environmentally harmful.

Speaking of wild veggies, I am surprised that we don't see more foraged greens in specialty markets like Three Rivers. Besides watercress, there is upland cress (or "creasy greens" to oldtimers hereabout), along with poke salad, dandelions, wild asparagus, wild onions and many more. I used to go on foraging trips with my grandmother, who believed that eating a good mess of wild greens was beneficial to one's health. I also wonder why ramps never seem to appear in the produce section, despite having a degree of popularity among upscale chefs in the big cities.

Thursday, April 12, 2012

Lettuce Season

I have always thought of April as the best month for lettuce in the garden, and this year is no exception. We started some plants in January and transplanted them to one of the greenhouses. The resulting bed, shown at right, has been yielding delicious salads for a couple of weeks now. Lettuce is super-easy to grow, so we plant a lot more than we can use. This allows us to go out to the garden right before dinner and pick individual leaves for a perfect salad. It helps to have a lot of plants to select from. If you only take one leaf per plant, the plant hardly notices. They just keep on growing, providing a continuously available supply of tasty leaves.

It is much easier to clean lettuce when harvested as individual leaves, rather than cutting the whole head. I try to select leaves that are not too close to the ground, avoiding both sand and insects. Slugs like to hide near the soil line, too. Further, removing a leaf here and a leaf there helps maintain the decorative look of the bed. Lettuce is one of the prettiest vegetables, and can be used to border a flower bed, for example.

The two varieties in the picture are 'Red Sails' and 'Oakleaf.' Seeds for both came from Mayo's here in Knoxville. They look great together in the garden and on the plate.

At left are lettuce seedlings that we started on March 10. They are ready to be transplanted, which will take place this weekend. These plants will go into a raised bed without added protection, since the weather has warmed up enough that a hard freeze is unlikely. (I should not have written that. Now I have jinxed the whole Valley.)

The varieties in the flat are 'Red Romaine', 'Freckles', 'Michelle', 'Rougette de Montpelier', and 'Deer Tongue.' The empty cells resulted from spotty germination, a common problem when seed for some varieties is stored for more than one season. I have learned that old-fashioned cultivars such as 'Black Seeded Simpson' and 'Buttercrunch' produce seed that retains viability longer than some of the newer ones.

The diversity of leaf shape and color combinations in lettuces is enormous, another reason the plants can be used decoratively. And during April in East Tennessee, they all flourish. If I had to grow only one spring vegetable, it would be lettuce.

Wednesday, April 4, 2012

Strawberries in Containers

The strawberries we enjoy today result from a long history of selection and hybridization among several of the fifty-odd natural species. Everbearing (or day-neutral) strawberries produce a bumper crop in early summer, another smaller crop in late summer and a few berries here and there throughout the season in between. Because of the long harvest season, they are a good choice for home gardeners.
Regardless of the variety, strawberries grown in the ground must be relocated about every three to five years. The plants are subject to viral disease and pests that can reduce yields significantly. Many of these problems persist in old, dead foliage or in the soil. Regular renewal of the plants and their growing medium offers the best natural defense against these problems. In terms of standard crop rotation, strawberries should be separated by five years from soil that has previously grown any member of the potato family. This is because several important crop diseases are common to the two groups of plants.  Crop rotation can be a real problem for the backyard grower with limited space. In the case of strawberries, container growing offers a great alternative, since plants can be repotted in new, sterile growing mix every season or two.
Plant breeders have produced new lines of strawberries that are better suited to container cultivation than their traditional counterparts. Dutch hybridizers have produced varieties that not only bear luscious, tasty strawberries but also have large, showy flowers. This makes the plants decorative as well as productive. The variety shown in the photo at left is “Tristan.”
Strawberries need full sun and a well-drained sandy soil of slightly acidic pH, about 6.0-6.5. Any good commercial potting mix will work for strawberries, or you can make your own by mixing equal parts of sifted compost, horticultural peat and sand. Rainfall or irrigation should provide an inch or two of water per week during the growing season. Purchase certified disease-free plants in late winter or early spring, before they break dormancy. Although plants will grow and bloom in a small container, choose a pot that holds at least a gallon of growing medium for best results. Smaller containers may need watering more frequently than you would prefer.
I try to avoid the traditional “strawberry jar” (an urn with extra openings in the sides for planting) because they seldom hold enough soil to accommodate the roots of all the berry plants tucked into them. I also avoid hanging baskets, because I find they dry out too quickly and thus demand too much attention during the hot summer months.
Remove runners from container plants as they form. Allow the occasional runner to root in a small pot before detaching it, if you want to increase your stock of plants. Just set the crown of the runner on the soil. When it roots itself sufficiently to resist a gentle tug, cut it free.  Such plants will bear the following season, typically.
Feed everbearing strawberries regularly. Due to the repeated flushing of the container with water, nutrients will be lost. Watering with compost tea or a similar soluble fertilizer every other week will keep plants productive. Or use a timed-release fertilizer.
After the first frost sends plants into dormancy, remove any dead foliage and place the containers in a sheltered spot for the winter. Cover them with a blanket of pine needles or autumn leaves. You can wait until the plants break dormancy to return them to their sunny position on the porch or balcony, or you can bring a plant or two indoors in early January. Place the pots in the sunniest location available, protected from frost. This will allow you to harvest the first berries about a month to six weeks earlier than normal. We currently have berries ripening along with spring lettuce, allowing us to enjoy a delicious salad topped with freshly picked berries. See the accompanying photo of a plant forced as just described, taken yesterday. This plant, by the way, is growing beautifully in a nursery container holding only a half gallon of growing medium, demonstrating how well adapted to container culture this breeding line really is. The variety shown is "Loran." The fruits are slightly tart, and bursting with strawberry flavor. If you get too much rain while fruits are ripening, they tend to become watery. Another advantage to containers is that they can be moved out of the rain when needed, to avoid this problem. 
A well-grown plant in a roomy container can produce about one pound of fruit or more per season. Strawberries can be frozen or made into jam or preserves. Rich in vitamin C and phytochemicals, fresh strawberries can be added to salad or turned into a cold fruit soup (see the recipe below). They also star, of course, in desserts like strawberry shortcake.
Strawberry Soup
For 4 servings:
1 pint fresh strawberries, stemmed
2 cups apple or white grape juice
Juice of one small lemon
10 large, fresh mint leaves, plus small leaves for garnish
Salt (if desired)
Sugar (if desired)
Sour cream or yogurt to serve (if desired)
Reserve four perfect strawberries for garnishing the dish. Roughly chop the remaining strawberries and process in a food processor or blender, in batches if necessary, with the juices, the mint leaves and a pinch of salt, until you have a smooth puree. Chill until very cold. Taste and correct the seasoning with salt, lemon juice or sugar, as you deem necessary. Slice the reserved strawberries lengthwise, beginning at the pointed end, stopping before you completely cut through the stem end. Ladle the soup into chilled bowls. Place a dollop of sour cream or yogurt, if using, in the center. Fan out the berries gently and float one on each bowl of soup. Garnish with small mint leaves and serve.