OREGON STATE UNIVERSITY

Troubleshooting in the Summer Vegetable Garden

07/18/2008

 

CORVALLIS, Ore. – During the height of summer, many home gardeners have concerns about why they have less-than-perfect vegetables. They call or visit the nearest Master Gardener help desk at the local county office of the Oregon State University Extension Service with questions galore.

OSU vegetable breeder Jim Myers offers troubleshooting strategies for growing carrots, cabbage and tomatoes. Plus, he gives advice on how to grow these vegetables better next time.

Carrots: Gardeners are often dismayed when they harvest hairy or misshapen carrots. Imperfect carrots, or carrots with multiple roots – many of them twisted around each other – may come from several causes, including spacing, soil type, fertility, pests and disease.

Your carrots could be overcrowded. Next time, try thinning them to an inch apart after the leaves reach about three inches high. Did you plant them in clay soil? If you have heavy clay soil, the clay sometimes forces the roots to grow crooked. Amend clay soil in next year’s carrot patch with well-broken down leaves, well-rotted compost. Carrots do well in light (sandy), fluffy soil that is not too full of amendments.

Root-knot nematodes may cause deformed carrots. You can either verify this with a soil test and then you might have to solarize (treat soil with the sun’s heat using plastic sheeting in the summer), or rotate your carrots to another area next time.

Did you fertilize right before you planted your carrots? Excess nitrogen (over fertilization) can cause carrots to form multiple roots or get “hairy.” If you add manure-laden compost to your soil, do so in the fall, then let it overwinter before planting carrots in the spring. Carrot roots will also become hairy in waterlogged ground.

Did you leave your carrots in the ground too long? Carrots are biennials. The first growing season, they grow a taproot. Next they put out secondary roots off the taproot, and then put up the flowering stem the second year. If you planted your carrots last fall, then overwintered them in the ground, they might be sending out whitish secondary roots by now and maybe a stem. Some varieties are more prone to bolting than others.

Cabbage: Growing good cabbage with nice heads seems to be a challenge for many home gardeners. Some complain that their cabbage doesn’t set heads at all. And others say that their cabbage heads set, but they crack open.

Are you watering your cabbage too much? Excess irrigation after a period of drought (little or no watering) can cause the heads to swell until they crack. Cabbages also crack when they are mature. Try watering them less and harvesting them earlier.

Others have cabbage plants that don’t set a head at all. Poor heading in cabbage may be caused by several factors, including overcrowding. Thin your plants early in the season to at least 18 inches apart.

Is your soil too dry? Are you watering deeply enough? Long infrequent watering is better than shorter surface watering for veggies like cabbage. Hot weather thwarts the formation of cabbage heads, causing them to be stunted or misshapen. Adequate watering may overcome some of the effects of heat.

Disease may also play a role in stunting cabbage growth. Pull up one of your stunted plants and examine the roots. Do they look “clubby” with large swellings, different than normal healthy roots should look? You may have club root fungal infection. If so, don’t plant any of the brassica family in that spot again for seven years. Root rot is another infection that thrives in clay soil. It can kill much of a plant’s root system. Rotate this area of the garden to another type of plant.

Tomatoes: Some of the problems you might encounter with your tomato plants while waiting for those juicy red fruits to develop include:

  • Blossom drop: usually caused by dry soil and dry winds, but also may be caused by sudden cold spell, heavy rains or too much nitrogen. Usually not all blossoms will fall off, so just be patient for the next set of flowers.
  • Blossom end rot: the end of the fruit furthest away from the stem gets black. Caused by irregular watering practices and calcium deficiency. Water deeply and regularly. Add lime to soil in fall to increase calcium level in the soil for next year’s crop. Most common in western Oregon.
  • Leaf rolling: most often the result of heavy pruning or root injury. Plants may lose leaves but will recover.
  • Sun scald: Green tomatoes can get sunburned, especially those plants with leaf spot diseases or those recently pruned.
  • Early and late blight: fungal diseases. Look for water-soaked looking spots on lower leaves and stems. If you see these, pick them off. Avoid overhead watering and monitor and remove diseased leaves.

To see photos of vegetables with various diseases, visit the OSU Extension Service Online Guide to Plant Disease Control at: http://plant-disease.ippc.orst.edu/plant_index.cfm, then type in the vegetable you want to know about.

Or, call your Master Gardener help desk at your local county office of the OSU Extension Service for help. To learn how to best utilize this service, go to: http://extension.oregonstate.edu/mg/questions