Recent research shows Apache, a new arrowleaf clover resistant to bean yellow mosaic virus, can provide cattle average daily gains of nearly three pounds per day under moderate stocking rates.

These gains were accomplished without the use of nitrogen fertilizer with a stocking rate of two animal units per acre during a three-month period from March through May, noted Monte Rouquette, the Texas Agricultural Experiment Station scientist who conducted the grazing study.

For the study, one animal unit was defined as 1,000 pounds of animal. Suckling steers and heifers were used for the study.

At lower stocking rates of 1.2 animal units per acre, average daily gains topped 3.5 pounds. At the high stocking rate of 2.8 animal units per acre, average daily gains dropped to about 1.75 pounds per acre.

Cattle on the study received no extra protein or supplements, only the standard free-choice mineral supplement, noted Ray Smith, clover and legume breeder with the Texas Agricultural Experiment Station, and developer of Apache.

Released in 2002, Apache promises to make arrowleaf clover a viable part of forage production in East Texas and other southern states.

As early as the 1960s, it was common practice to mix arrowleaf seed with crimson clover seed and grow it widely throughout many southern states, from East Texas to Georgia. By mixing the early-maturing crimson clover and late-maturing arrowleaf, ranchers and farmers could have forage from February through early June. Multiple disease problems, including plant viruses and fungal rot, effectively put a stop to this practice a decade ago. Of the diseases, Bean Yellow Mosaic Virus (BYMV) was one of the most prevalent and damaging problems.

BYMV didn't affect crimson clover, but it killed arrowleaf clover, stunted it, or caused it to mature early.

Left production gap

“It left a production gap from when the crimson matured to when arm-season grasses came on in June that was never filled,” Smith said.

Arrowleaf clovers such as Yuchi, Meeche and Amclo, are affected by BYMV in several ways. Some plants are killed outright by lethal wilt. Others go on to survive but will suffer a variety of symptoms, including misshapen leaves, yellowed leaves or leaves spotted in a yellow mosaic pattern. Of the surviving plants, yields are reduced by as much as 50 percent, but worse, the productive lifespan of the survivors is shortened, leaving months during the spring without forage production.

Apache is resistant to the lethal wilt caused by BYMV and tolerant to the secondary symptoms such as leaf discoloration and stunting.

“It's tolerant to the degree that we expect it to fill the production gap left by susceptible varieties such as Yuchi. Producers should once again be able to rely on a crimson/arrowleaf mixture for forage production from late winter and early spring,” said Smith, who is based at the Texas A&M University System Agricultural Research and Extension Center at Overton in Rusk County.

Smith began work on arrowleaf clover disease resistance in the late 1980s. He began with the conventional plant breeding method of growing arrowleaf cultivars in the field and selecting those plants that appeared healthy while those around fell to disease infections.

After several years, it became apparent to Smith that the conventional method wasn't working. Aphids spread the BYMV virus, and the insect habits meant that some plants were infected while those nearby might not be.

“So we were selecting those plants that both had tolerance to BYMV and those which just happened to dodge the bullet, so to speak,” Smith said.

Undaunted, he moved to greenhouse trials where he could strictly control the spread of BYMV. Plants were inoculated with a slurry of tissue from BYMV infected plants. In conjunction with the greenhouse trials, Smith continued field trials, but mechanically inoculated those plants with BYMV as well.

Resulting cultivar

The resulting cultivar, which until recently went by the unassuming designation of TX-AL98-1, is resistant to BYMV-induced lethal wilt, tolerant to BYMV-induced dwarfing, and other symptoms such as rough, wrinkled leaves, and yellowed, mosaic patterned leaves. It shows improved field survival when infected with BYMV and has greater early spring (March) forage production compared to Yuchi, the most commonly grown arrowleaf today. Apache flowers 10 to 14 days earlier than Yuchi, and its total season forage production is greater or equal to Yuchi.

Seed should be available in good quantities this year for fall planting. For prices and availability contact East Texas Seed Co., P.O. Box 569, Tyler, TX 75710-0569. The company's phone number is (903) 597-6637. The email address for East Texas Seed Co. is seeds@easttexasseedcompany.com.

Arrowleaf clovers can be interseeded in bermudagrass pastures either by broadcasting alone, lightly disking and then broadcasting or by drilling, said Larry Redmon, forage specialist with Texas Cooperative Extension.

Though just broadcasting the seed and doing nothing else is not the most effective method, it does often produce good results. Redmon and Smith recommend using about 10 pounds of Apache seed per acre. At $2 per pound, this means the total cost of establishment could be as little as $20 per acre. The seed can be mixed with a light fertilizer application if immediately broadcast or planted.

A light disking has two advantages. It sets the warm season grass back a little and exposes bare soil.

“They'll get a little more forage if they disk and perhaps a little earlier forage. The cost for disking will add another $7 to $8 per acre in establishment cost.”

Low-till drills

Low-till drills are becoming a scarce item in East Texas, but if one can be found, producers can realize another small improvement in stand and dry matter production.

In most cases, Redmon recommends the simple broadcast method.

“Producers can realize a savings of $70 to $80 per animal with Apache over feeding hay,” Redmon said. “Contrary to what some people think, cattle do not pull arrowleaf out by the roots, so producers will also gain some soil nitrogen for their summer forages.”

Robert Burns is a writer for Texas A&M University. e-mail: rd-burns@tamu.edu.