Tomato Leaf Curl

Have you ever seen the leaves of your tomato plants begin to curl or roll up? Several factors including environmental stresses, viral infection and herbicide damage can cause this odd looking condition, which while it may not mean the complete demise of the plant, can severely stunt growth. Examine the plant to determine the cause of the curling or rolling of the leaves…is it just new leaves or all of the leaves? Do the leaves roll upward or downward? Are any other parts of the plant, including fruit, showing signs of curling?

Physiological Leaf Roll
Over fertilization, and excessive heat, drought, careless pruning, and transplant shock are several of the environmental factors that can cause physiological leaf roll in nightshade varieties like tomatoes. Usually symptoms first appear n the lower leaves with an upward curling of leaflets followed by an inward lengthwise rolling of these small leaves toward the middle vein. The affected leaves often become thickened and have a leathery texture, but may retain normal, healthy green color.

Vine tomato (indeterminate) varieties seem to exhibit physiological leaf curl more frequently than bush tomato (determinate) varieties, and while this condition can occur at any time of the growing season, it usually occurs during the transition from spring to summer. While it is an odd looking condition, tomato leaf curl has little to no impact on plant growth and tomato fruit production. Fully hardening off tomato seedlings before planting, taking care to avoid over fertilizing, and maintaining consistent moisture level in the soil, will greatly help prevent tomato plants from developing this physiological problem.

Viral Infections
Several viral infections may also cause leaf curling in tomatoes. Yellow leaf curl virus, for example is transmitted by whiteflies, and new leaves on infected plants become cupped and pale green in color. The entire plant may also show signs of stunted growth, decline in fruit production, yellowed leaf edges, and purple colored veins on the undersides of leaves. Tomato mosaic virus is another disease that causes curling of leaves, as well as other symptoms, including mottle colored leaves, and internal browning of infected fruit.

There is no treatment for virus-infected plants. It is best to remove and destroy infected plants, and because weeds often serve as hosts to the viruses, managing weeds around your garden can help prevent transmission of the virus by insects. It is also important to disinfect tools that may have come into contact with diseased plants in order to help prevent spreading the virus.

Herbicide Damage: Symptoms of tomato plants that have been exposed to herbicide include downward curling of leaves, twisted growth, deformed fruit, and  stems that split or have turned white. Ultimately the plant’s survival will depend on the level of exposure, and while damage cannot be reversed, new growth on the plant may be normal. Be cautious when spraying herbicide as the mist can drift beyond the target area.

Cultivating Sweet Potatoes

HISTORY

While the sweet potato originated in the tropical and subtropical areas of meso and South America, the remarkable journey it made around the world and into the diets of many cultures would impress even the most well-heeled jetsetter. While it is often interchangeable with potatoes in culinary applications, the sweet potato tuber, also called kumara, thrives in warm, humid climates where it is difficult to grow the true potato.

Sweet potatoes are thought to have been domesticated from I. trifada, which is native from Mexico down to Venezuela, and were carried around the world to the South Pacific islands, Egypt, India, New Zealand, Sri Lanka, Japan, and China where it reportedly arrived around the end of the 16^th century.  They reached southern Europe by the early 16^th century – before the arrival of the true potato.

The Taino Indians of the Greater Antilles and Bahamas named the sweet potato batata. The  Spanish gave the same name to the Andean tuber or true potato, thus both tubers ultimately became known as potato, with the sweeter, tropical plant later used termed the ‘sweet potato’ to distinguish the two markedly different varieties of tuber.

Like the potato, there are many varieties of sweet potato developed for various types of food preparation around the world.  Cultivars high in starch are sweeter and commonly used for making crisped chips, candying and roasting, while other varieties are better suited for soups,  stews and mashing.

CULTIVATION

Sweet potato typically grows as a trailing vine, but semi trailing and even compact bush types have been developed to make the most of limited garden space. They thrive in warm weather and when planted well after danger of frost, quickly shade out weeds as the season progresses.  

Outside the tropics, sweet potatoes are commonly grown from rooted shoot cuttings called slips, which are widely available from garden centers and reputable mail order suppliers, and are a fast, reliable method for establishing a backyard sweet potato crop. Reputable mail order suppliers, like Southern Exposure Seed Exchange, for example, often sell certified organic sweet potato slips that are well adapted for a specific region of the country.

Sweet potatoes prefer loose, well drained soil, and a raised planting area that’s 12” deep or more, filled with a light organic soil blend will ensure your sweet potatoes have room to fully develop.

Transplant slips in the garden 3” deep, 10”-18” apart in rows at least 3’ apart. This spacing is crucial to allow room for the sprawling vines to develop. Slips should be transplanted in the evening, and watered in well, with the soil kept moist for the first several days as the plants get established.

Once established, sweet potatoes can perform well with little water or fertilization, but irrigation and even moisture can help prevent splitting and cracks, and side dressing the plants with compost will improve both size and overall yield.

HARVESTING

Sweet potatoes typically require between 90 and 120 days to reach maturity, depending on the variety, and the best way to check the size of your crop is simply to dig one of the plants after the recommended growing time has passed. If they’re still a little small, wait another week or so and try again. It’s best to harvest on a sunny day when the soil is relatively dry. Begin by pulling the vines aside so you can see where to dig, and using a spading fork, start about 12” away from the main stem of the plant, digging 6” straight down, then angle toward the center of the plant and lift the potatoes up out of the ground. Separate the sweet potatoes and dry in the sun for about an hour, handling them gently to avoid bruising.  While they’ll continue growing if left in the ground past the recommended growing period, growth will slow as the weather cools, and for optimum storage quality, they should be harvested before the soil temperature drops below 55 degrees.  

Don’t’ want to wait four months to enjoy your sweet potato patch? The tender shoots and leaves of the sweet potato vine are also commonly harvested,  and used as cooking greens much like spinach ; chopped, steamed, sautéed, etc.  Just be sure to leave enough of the vines and shoots above ground to ensure a vigorous plant that produces a good crop of sweet potatoes below ground later in the season.

CURING & STORAGE

Curing improves the sweetness and storage quality of sweet potatoes, and also allows for the healing of scratches and any other damage. After harvesting, allow the sweet potatoes to dry completely, then  shake off any excess soil.  Never wash sweet potatoes before curing.  Cure them by keeping at 85 degrees and 90% relative humidity for a week to ten days.  A space heater can be helpful in creating these conditions.  For long term storage, choose firm, well shaped potatoes with even coloring and free of bruises.  Small or damaged sweet potatoes can always be washed and used right away. Store cured sweet potatoes in a cool, dry place away from light. Properly cured sweet potatoes will store between 5 and 12 months unrefrigerated.

GROW YOUR OWN SLIPS NEXT YEAR

Start about 8 weeks before planting time, by selecting 1.5” diameter sweet potatoes from high yielding hills. First soak the sweet potatoes in water for two hours, then place them in a pot or flat half filled with soil or compost.  Cover the  sweet potato with another two inches of soil and keep evenly moist in a warm, sunny place indoors. When it’s time to plant, cut the slips about an inch away from the ‘mother potato’ to avoid transferring any diseases. Slips should be about 8-10” long when they’re cut and planted.

Ready to get started on your own sweet potato crop? We recommend the high quality sweet potato slips offered by these reputable suppliers :

Sow True Seed Co.

Southern Exposure Seed Exchange

Garden Adversaries

Sometimes people just don’t get along. It’s the same with plants, and placing certain ‘antagonists’ together in your garden might have more abrasive results than having the Hatfields & McCoys over for a dinner party.

While the idea of companion planting varieties that form a beneficial relationship is backed by science, the same is true for garden adversaries.

Beets, for example, thrive when planted together with cabbage, kohlrabi, garlic, lettuce, and bush beans, but could do without the company of pole bean varieties.

Brassica family varieties like cabbage, kale, collards, and cauliflower perform well when planted with cucumbers and potatoes, but have irreconcilable differences with strawberries, tomatoes and pole beans.

More than a few popular vegetable varieties are selective about their bedmates, and the list may surprise you.

Corn and tomatoes are two classic summer crops that are especially popular in the southeast, but for best results, the two should be separated in the garden.

Carrots are perfectly happy alongside peppers, onions, peas and radishes, but need some space from dill.

The lead role in many a summer garden, the tomato, has plenty of friends, but won’t want to share a dressing room with potatoes, kohlrabi, corn or cabbage.

The Cucumbers is another popular summer actor, that’s happy to share the stage with tomatoes, corn, beans and lettuce, but will take issue when cast in a scene with potatoes and a variety of aromatic herbs.

While they may join forces once they arrive in the kitchen, while still in the garden, bean and onion family varieties will perform better with plenty of space in between them.

Martha and Nancy : Next Door Neighbors, Friends...and Now Organic Gardeners

Relationships with our next door neighbors can sour faster than the pint of milk that spent spring break in your kid’s lunchbox. While a good fence always helps, barking dogs, untidy lawns, fallen leaves, and late night parties can irk even the most level headed next door neighbors.

Not the case with Cotswold neighbors Martha and Nancy.  

These two moms share a genuine friendship that goes beyond a polite smile and wave. They share family milestones, the occasional recipe, and sometimes even a company referral.

Through her network of friends, Nancy had heard several outstanding reviews about our niche organic gardening services, and one sunny afternoon, shared that news over the fence with Martha.

That referral turned out to be doubly great news for us, because we welcomed two new gardeners into the Microfarm family. Logistically, it was nice too, because we could have the delivery of 4 cubic yards of premium organic soil dropped in one spot right between the two homes. 

Nancy selected two 4’x6’ Kitchen garden style raised beds for an area adjacent to her driveway, while Martha had the perfect place for a single 4’x6’ Kitchen garden bed in a nook next to a staircase that descends into a landscaped pathway. We planted a variety of leafy greens and root vegetables for both neighbors, including Bloomsdale spinach, lacinato kale, carrots, and an assortment of lettuces.

Many thanks for the business and the convenience of being next door neighbors, Martha and Nancy - we hope your new organic gardens make your friendship even better!

Companion Planting

Like the individuals that form any good (or bad) human relationship, plants also have chemical properties that can create mutual benefit or a toxic relationship when they’re grown together.

Like that mysteriously perfect marriage your friends seem to have, these companion plant arrangements may seem too good to be true, but solid scientific research supports what growers have learned over many generations.

All plants produce a range of waste products that are emitted through their foliage, stems and roots, which can chemically change the surrounding soil environment.  Certain plants -most famously herbs-but also other varieties including African and French marigolds, nasturtiums, and even tomatoes contain strong smelling substances that are emitted by their leaves that overpower the scents emitted by other plants, confusing insect pests.  The time tested practice of planting strongly scented herbs among a vegetable garden will most certainly help avoid and mitigate insect and animal pest problems.

Borage is a tall, aromatic herb, for example, that fits nicely in a tomato patch, and repels tomato horn worms. Basil deters flies that lay eggs on tomato leaves, and is reported to actually improve the flavor of tomatoes as well. The powerful scent of the wormwood plant overwhelms the sense of smell that many mammals rely on for survival, thus discouraging them from browsing through your vegetable garden. Are you losing plants to deer, but not ready to invest in a 7’ deer fence? Strongly scented yarrow, oregano, rosemary, and lavender and mint will discourage them. Puzzled over how to reign in a mole or gopher problem? Castor oil plant will do the trick.

Not only will many aromatic flowering herbs like thyme, mint, sage, rosemary and dill discourage harmful insect pests, but they’ll actually attract beneficial insects like parasitic wasps, preying mantis, and tachinid flies that prey on them and help control their population naturally. Herbs like bee balm, thyme and mint, as well as flowers like daisies, petunias, cosmos, sunflowers, and nasturtiums will also attract pollinating bees into your garden in addition to beneficial predatory insects.

Sometimes a taller companion plant simply offers a little relief in the form of shade to a shorter neighbor, as in the case of beet tops shielding lettuces from a scorching afternoon.

But the benefits of some companion plants go beyond scented foliage. The roots of marigolds, for example, exude a chemical that discourages harmful nematode varieties. If you’ve ever found a healthy plant suddenly wilt and die, only to dig up the roots to find clusters of ball like knots, you’ve seen the damage that soil nematodes can cause.

Sold on companion planting or at least curious enough to give it a shot?  The companion planting guide below lists beneficial plants along with problematic insects that each one deters.

Aster                                     variety of insects
Basil                                      flies, mosquitoes, asparagus beetles
Borage                                  tomato worms
Calendula                           tomato worms, asparagus beetles
Catnip                                   ants, aphids, flea beetles, Japanese beetles
Chives                                  aphids, Japanese beetles, whiteflies, mites
Chrysanthemum              Japanese beetles, Mexican beetles
Coreopsis                            variety of insects
Coriander                            aphids, carrot flies, Colorado potato beetle, mites
Garlic                                    aphids, borers, Japanese beetles, spider mites
Geranium                           cabbage worms
Henbit                                  variety of insects
Horseradish                       potato beetles
Hyssop                                 cabbage moths
Lavender                             moths
Marigold                             nematodes, Mexican bean beetles
Marjoram                            variety of insects
Mint                                      ants, cabbage moths, aphids, flies
Nasturtium                         squash bugs, beetles
Oregano                              cabbage butterflies, cucumber beetles
Parsley                                 variety of beetles
Radish                                  cucumber beetles
Rosemary                            bean beetles, cabbage moths, carrot flies
Rue                                        flies, Japanese beetles
Sage                                      bean beetles, cabbage moths, carrot flies, slugs
Sunflower                           aphids
Tansy                                    ants, fleas, flies, Japanese beetles, moths, squash bugs
Thyme                                  cabbage worms