January 1997 - Indiana Yard and Garden - Purdue Consumer Horticulture

January 1997

Q: In digging sweet potatoes last week, I, too, found the sweet potatoes hulled out or eaten. There had been a mole run along the sweet potato ridge, and every so far, I would see a round hole made in the mole hill. I dug out shrews, and the potatoes had been freshly eaten on. So, I think the shrews use the mole hill to travel in, and they eat the sweet potatoes and Irish potatoes.

Also, why do sweet potato skins turn dark? Mae Atkins, Birdseye, Ind.

A. I agree! The moles are blamed for doing the damage, but in fact, they just create an easy way for other rodents to get to the sweet potatoes.

The skin discoloration may be caused by black rot or scurf. Both diseases are caused by a fungus. Black rot causes black spots with tiny black specks on roots in the ground and in storage. The affected sweet potatoes taste bitter. There is no chemical control available. The fungus overwinters in sweet potato debris and weeds for more than two years, so garden sanitation is important. Remove all pieces of debris, and plant sweet potatoes in a different area for at least two years. Purchase certified slips or sweet potatoes.

Scurf causes dark brown to black spots or irregular patches that stain the skin only, not the inside of the sweet potato. The flavor of the tuber is not affected. Use scurf-infected roots immediately. Next year, plant sweet potatoes in well-drained soil, purchase disease-free slips, and rotate the crop location if you can.

Q: I used to be able to raise a nice crop of carrots, but in the last four or five years, a small white worm, approximately a quarter-inch long, burrows into the carrot, usually near the top. A lot of the carrots end up rotting once they are infested with the worm. My mother-in-law has gardened for 45 years and has just had this same difficulty, too, in the last few years. Do you know what this worm is and how I could treat my garden? I do rotate where I plant my vegetables, so it’s not like I’m putting my carrots in the same spot every year. Benita Bahler, Wolcott, Ind.

A: Carrot weevils are plump, white, legless grubs, about 1/3 inch long. They riddle the upper part of the carrot with zigzag tunnels and feed on carrots, parsnips, dill, celery and parsley. The eggs are laid by a brown beetle on the carrot tops. In May and June, the eggs hatch and the grubs travel down to the root. After becoming adults, they re-emerge to lay a second generation of eggs in August. The adults overwinter in garden debris.

There are no insecticides registered for carrot weevils. Clean up garden debris in the fall, and don’t compost infested debris.

Q: I really enjoy reading your column in REMC and look forward to it. I would like to know where I could get some potato and onion sets. Here’s hoping to hear from you soon. Howard Alley, Dearborn, Mich.

A: Onion sets should be available at most garden centers in the spring or through many of the popular garden catalogs. The size of the onion set will determine the size of the harvested onion, but it is the opposite of what you would expect. Large sets tend to produce small bulbs, while small sets tend to produce larger bulbs. Onions grown from sets generally do not make good storage onions and are best raised for green onions or for bulb onions that will be used right away. Sets also can be planted in late summer or early fall to enjoy a fall harvest.

Potatoes are started from seed potatoes, also available at garden centers. To start a new planting, cut the seed potato into pieces so each individual piece has at least one healthy-looking bud. That bud will become the shoot of the new plant and, as the stem develops, it also will produce new roots.

Q: I heard you speak at Purdue recently, and you mentioned that you were expecting your second baby soon. Congratulations! I’m sure you still garden while you’re pregnant. I wondered if you take any special precautions. Should I be concerned about bacteria in the soils or mulches? Do you refrain from applying certain pesticides or herbicides? I know you aren’t a medical doctor, but I’d like to know if you have practical advice to give. (Having recently discovered I am pregnant, can I use the excuse to get my husband to help plant fall bulbs?) Martha Chen, West Lafayette, Ind.

A: I planned to plant bulbs last fall to help pass the last month of pregnancy, but the ground was wet and our son was born early, so the bulbs were never planted. As the time approached, I realized bulb planting required lots of up-and-down activity, and I would have been happier with easier garden tasks.

I really can’t give medical advice, but I do know that you should wear gloves when gardening to avoid soil contaminated with cat feces. Personally, I avoid all pesticides when pregnant. I’ll gladly tolerate a few bugs and diseases on my plants to avoid any harm to the baby! I still enjoyed the garden, but I didn’t accomplish much while I was expecting. Ask your doctor for guidelines, and use this time to take it easy. Try sitting in a lawn chair and giving your husband directions. It may not work, but you’ll never know until you try!


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