OKLAHOMA ALFALFA

OKLAHOMA ALFALFA

HAY & SEED ASSOCIATION
368 AG Hall OSU Agronomy Department Stillwater, OK 74078

Volume 20 No. 8 August 1996 We welcome contributions and suggestions. Comments about and contributions to the NEWS are welcome and can be submitted to any of the directors.

NEWS

Mark October 24 on your calendar for the Alfalfa EXPO '96. It will be held in conjunction with the Beef Cattle Symposium at the Grady Co. Fairgrounds in Chickasha. The overall event will include an Educational Program, Hay Show, Auctions, and Lunch.

The education program will include programs for Alfalfa Producers and Cow-Calf operators:

EXPO '96 will also include an auction similar to the one held during the Annual Meeting last February, with proceeds going to the Oklahoma Alfalfa Hay & Seed Association for research. The auction last February generated about $18,000. Spread the word to businesses and individuals who may want to donate to the auction.

Large auction items already offered include the lease of baling equipment and tractors. The Board of Directors hopes to have many items for the large equipment auction as well as the silent auction that will included seed, chemicals, lubricants, etc.

Anyone wanting to donate items to the auction should fill out the form enclosed with this issue of the NEWS and send it to Oklahoma Alfalfa Hay & Seed Association, 368 Agric. Hall, Agronomy Department, OSU, Stillwater, OK 74078-6028.

This subject has been a reoccurring problem for alfalfa producers this year. Heavy infestations of corn earworms, webworms, and other defoliators began their assault on alfalfa nearly a month ago. Since that time, continued pressure in some areas of the state has led to multiple applications for control or early cutting to attempt alleviation of the problem. In an attempt to provide some information about controlling these pests, a test was conducted in Stillwater on established alfalfa with a high population of defoliators.

A 5-acre field of established alfalfa at the Agronomy Research Station, Stillwater was used to evaluate the efficacy of chemicals having no or short preharvest intervals (PHI). Chemicals and their rates are reflected in the table. Two of the chemicals, Pounce and Malathion, at these particular rates have a zero PHI, while the remaining compounds (at these rates) have a 7-day PHI. Approximate costs per acre at these rates are also reflected in the table.

Pretreatment evaluation of the field site revealed an average of 6.9 defoliators per sweep -- 64% of these were corn earworms, 30% were alfalfa webworms and 6% were alfalfa caterpillars. Recommended thresholds for treatment of defoliators in alfalfa are 5-6 larvae per sweep. Alfalfa was in the early bloom stage at time of treatment. Applications were made on July 31, 1996, using a CO₂-pressurized backpack sprayer calibrated to deliver 20 gallons per acre at 30 psi.

Evaluation of control was conducted 8 and 14 days after treatment using a 15-inch sweep net. Ten sweeps were made in one-half of each 30 ft. long by 12 ft. wide plot area.

Defoliator numbers dropped dramatically from the pretreatment counts, even in untreated areas. This was probably from the caterpillars pupating and/or disease pressure. Analysis of numbers, eight days after treatment revealed significantly better control in alfalfa treated with Pounce or Sevin than in untreated plants or those receiving Malathion. Although Lorsban (0.5 lb AI/A) had defoliator populations similar to Sevin XLR, eight days after treatment, it did not outperform Pounce at 0.10 lbs. AI/A. Fourteen days after treatment, all treatments were similar, adult populations were high, and evidence of diseased (dead) larvae was obvious. Hopefully, populations have subsided for now, and anticipated above-normal precipitation will keep insect disease levels high. Only time will tell. Scout your next cutting carefully.

Chemical	Application Rate	Cost	Defoliators per 10 sweeps
	(lb AI/Acre)	($/Acre)	8 DAT¹	14 DAT¹
Pounce 3.2	0.10	5.90	4.25c	1.25a
Malathion 5E	1.25	5.30	12.25a	1.25a
Sevin XLR	1.00	4.80	6.0bc	2.0a
Lorsban 4E	0.50	6.50	9.0ab	2.5a
Untreated	--	--	10.75a	3.0a
LSD	--	--	3.25	NS
¹8 DAT= 8 days after treatment, 14 days after treatment. Numbers followed by the same letter are not significantly different.

Many alfalfa producers have already sown alfalfa this year, and apparently many more are still planning to plant. This is an excerpt from the soon-to-be-published "Alfalfa Stand Establishment Questions and Answers," OSU Extension Circular E-949.

EXPLANATION: To ensure good soil-to-seed contact, clods should be less than 1/4 inch in diameter. This is often accomplished by a disking followed by spring-tooth and spike-tooth harrowing to further break clods and to help smooth the field. The final operation may be a corrugated roller or cultipacker to crush the remaining clods and finish firming.

Seedbed preparation should be done when there is sufficient moisture in the soil so that it crumbles when worked. There is usually a short time after each rain when soil moisture is just right.

It is important to have moist soil 1 to 3 inches below the surface at planting; however, it is not essential to have moisture at the surface. Most successful alfalfa plantings are made when the seed is planted into dry surface soil. Normally moisture required for germination and initial seedling growth comes from rain or irrigation after planting. If the soil is dry to a depth of 4 to 6 inches, it is difficult to prepare a good seedbed, and over an inch of rain to wet the soil enough for germination of the alfalfa may be required.

A good seedbed shows boot prints or the bars of a tractor tire. If the soil is too hard, no imprint is made. If the soil is too fluffy, no detail remains of boot prints or tractor tire bars.

Literally thousands of varieties and experimental alfalfa strains have been developed. Normally 15 new varieties are submitted annually for testing in Oklahoma. The following varieties should be available, have yielded and persisted well in tests through 1995, and are considered the best.

Garst 630 has been tested in Oklahoma since 1987 in 28 trials. Garst 645 has been tested in Oklahoma since 1991 in 14 trials.

Good As Gold has consistently performed well in Oklahoma since 1987 in 11 trials.

Cimarron has been tested in Oklahoma since 1979 in 47 trials. Cimarron VR has been tested in Oklahoma since 1988 in 21 trials.

Arrow has been tested in Oklahoma since 1988 in 6 trials. Aggressor has been tested in Oklahoma since 1991 in 5 trials.

October 24 Oklahoma Alfalfa EXPO. Meeting in conjunction with the Cow-Calf Symposium at the Grady Co. Fairgrounds in Chickasha. This will include auctions, hay show, educational program and complimentary lunch. Mark your calendar now. Details will follow in the NEWS.

If you are planning an alfalfa meeting, Call and give us the details. We would like to include it in the list. The Oklahoma Alfalfa Hay & Seed Association assists with meals and/or refreshments during county or regional educational meeting that included alfalfa. The Board asks that the event is listed in the NEWS and requires that the date and general program is sent to the Secretary at least 6 weeks in advance.