08/01/1996

Horticultural Researchers Report Results of Vegetable Research at the Wiregrass Substation

HEADLAND, Ala.- Lettuce, usually considered a cool-climate crop, will grow in the Wiregrass region of Alabama, was the news from Auburn University horticulturist Eric Simonne.

Simonne, who was one of several Auburn University researchers on hand recently for a Vegetable Field Day at the Wiregrass Substation in Headland, explained that many people believe lettuce will not grow well in Alabama, particularly in southern regions of the state, because it is typically a cool-season crop. To learn more about the potential of lettuce as a home-garden and commercial crop for Alabama, Simonne instituted lettuce variety studies at several substations in the state, including at the Wiregrass Substation. The substations are outlying research units of the Alabama Agricultural Experiment Station (AAES).

According to Simonne, several varieties were planted at Headland and also at other research locations across the state. Results of the plantings suggest that lettuce can perform well in warm climates if it is irrigated.

"The lettuce at Headland did well despite the fact that it was planted late in the spring and planted on black plastic mulch," said Simonne. He explained that the black plastic mulch can be an advantage for crops planted in early spring because it absorbs heat and keeps the soil warm even if temperatures drop. For crops planted later in spring, however, black plastic mulch can trap too much heat in the soil and limit yields.

Simonne noted that this is the first year of the study and the data are preliminary. However, these first-season results indicate that lettuce performs best when it is close to the irrigation source. During a tour of the research plots, Simonne pointed out how lettuce that was growing close to irrigation lines was larger and more vigorous than lettuce planted a few inches away from the source of water.

Simonne also discussed on-going variety work underway throughout the state on a wide range of vegetable crops. Simonne, who is a research fellow in AU's Department of Horticulture, coordinates vegetable variety trials state-wide.

"Variety trials are scientific, unbiased evaluations of advanced breeding lines and commercial cultivars," he explained. "When we do variety trials, we are not in the business of promoting a certain product. We are trying to find out which varieties will perform best for commercial and home growers state-wide." He noted that variety work in underway at nine substations throughout the state evaluating such crops as watermelons, tomatoes, lettuce, bell and hot peppers, potatoes and much more.

Also on the program at the field day was Beth Guertal, assistant professor of agronomy and soils at AU, who has been researching vegetable crop fertility issues.

"Nitrogen is really increasing in cost and we have been getting a lot of calls from growers asking if they can use different forms of nitrogen," she explained. To answer these questions, Guertal established nitrogen source studies on tomatoes and watermelons at various locations in the state. Results of the studies showed little or no difference in yields of the crops fertilized with a variety of nitrogen fertilizers.

"These results suggest that producers can take a look at the cheaper forms of fertilizers without limiting yields," she said. Guertal, noted, however, that these studies are also preliminary and more data need to be collected before recommendations can be made.

Another study Guertal discussed was an evaluation of slow-release fertilizers for strawberries. That study, which was conducted at three locations in the state, showed that strawberries fertilized with slow-release products yielded higher than those fertilized with traditional fertilizers.

"These fertilizers show some promise for strawberry production," she said, but she warned that the slow-release fertilizers are more expensive than traditional fertilizers.

Guertal also discussed studies of crop rotation ideas for vegetable growers. One study examined the effectiveness of certain crop rotations for the control of root-knot nematodes. She noted that methyl bromide, a chemical now used by many vegetable growers to control nematodes, will soon be unavailable to producers. "One idea for a natural control of nematodes is to rotate crops with vetches and other legumes," she said.

A greenhouse study looked at the nematode populations in soils planted with hairy vetch, Cahaba vetch and crimson clover. The study showed that legumes had little effect on nematode populations; however, the study is now underway in a field setting and Guertal said results may be different.

The final study discussed by Guertal was the use of crop rotations with sweet potatoes. This study has been underway for 14 years and results show that rotating sweet potatoes with bahiagrass can significantly increase yields. Results indicated that rotating sweet potatoes with two years of bahiagrass more than doubled yields compared to sweet potatoes that were planted on the same land year after year.

Also on the program was Gene Hunter, who discussed a cowpea breeding study that is attempting to help develop cowpea curculio resistance in southernpeas. Hunter, who is a senior research associate in AU's Department of Horticulture, explained that the curculio is an insect that lays eggs in the hulls of peas and causes the peas to have black spots on the seed, making them appear "wormy." His research is trying to develop new crossbreeds of peas that will be resistant to this insect.

Finally, Joe Kemble, assistant professor of horticulture at AU, talked about irrigation methods for vegetable crops. Kemble noted that there are numerous methods to time irrigation of crops, and the important key is managing water usage so that the plants receive plenty of water without wasting water.

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News from:

Office of Ag Communications & Marketing

Auburn University College of Agriculture
Alabama Agricultural Experiment Station
3 Comer Hall, Auburn University
Auburn, AL 36849
334-844-4877 (PHONE) 334-844-5892 (FAX)

Contact Jamie Creamer, 334-844-2783 or jcreamer@auburn.edu
Contact Katie Jackson, 334-844-5886 or smithcl@auburn.edu

August 1, 1996