OKLAHOMA ALFALFA

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QUESTION: Will herbicide used on a previous crop cause injury to newly-planted alfalfa?

SHORT ANSWER: Yes, damage (stunting) of newly-planted alfalfa has been observed in fields where persistent herbicides such as GLEAN and AMBER were used for weed control in wheat the previous spring.

"Rotational Crop Restrictions" exits on many herbicides used in Oklahoma. The reason for these restrictions is that there may still be enough herbicide residue in the soil to injure subsequent crops.

Examples of Rotational Crop Restrictions for Alfalfa
Previous Crop	Herbicide	Restriction
Wheat	GLEAN	Field Bioassay**
Wheat	AMBER	Field Bioassay**
Wheat	FINESSE	Field Bioassay**
Wheat	ALLY	34 months
Soybeans	PURSUIT	18 months
Soybeans	SCEPTER	18 months
Corn	ACCENT	12 months
Corn	BEACON	8 months
Alfalfa	PURSUIT	18 months
Alfalfa	SINBAR	24 months
Alfalfa	VELPAR	24 months

**Field Bioassay means planting alfalfa and observing to see that it emerges and grows normally.

The use of the sulfonylurea herbicides (such as GLEAN and AMBER) on the wheat crop before planting alfalfa has resulted in severely stunted alfalfa seedlings in a number of fields in Oklahoma. This has been particularly evident after dry summers following herbicide application. To be safe, always read and follow crop restrictions on herbicide labels. This includes keeping accurate records as to: What chemical was applied?; When was it applied?; How much was applied?

Many examples of alfalfa injury from herbicide carry-over probably occur each year. Often the "variety", "weeds", or "weather" are blamed for poor alfalfa stand establishment when in fact it was herbicide "misuse", including forgetting when, what, or how much herbicide was applied on previous crops. --From the Soon-to-be-Published O.S.U. Extension Circular 949 -- Alfalfa Stand Establishment Questions and Answers.

Alfalfa producers are now enjoying some of the highest prices for hay in recent history, and the age old question of whether to store or sell hay from the field should be examined. As with any marketing decision, hindsight is 20-20. A year from now, every hay producer will know which marketing method would have been better.

I certainly do not know what hay prices will do over the next year and do not know of anyone who does. Hay producers will have to make marketing decision based on the "price for good hay is stronger than we have seen in many years." High prices are due to dry weather (low production), high grain and meal prices, and low hay stocks.

The following table should help producers make informed marketing decisions. I have assumed 10% interest on money, a 10% shrink on hay, and a $5.00 per bale charge for getting big square bales in and out of the barn. Based on these assumptions, the break-even price for $110 hay in the field, 6 months from now, is $132/ton. The majority of the cost associated with storage occurs early in the storage period due to shrink and cost of hauling. After theses costs have occurred, the interest cost is the only cost that increases.

There was no charge for the cost of the hay barn included. Also, there was no charge for insurance on the hay. Insurance is a cost producers would need to add to the costs shown in the table.

Hay prices tend to be seasonal. HAYMARKET data indicates that prices for hay are above the yearly average from October through April. December prices are normally 14% above the annual average price, and January and February prices are 11% and 12% higher, respectively.

The seasonal low price occurs in May. May has averaged 12% below the yearly average price. June, July and August averaged 9%, 6% and 4% below the yearly average price, respectively.

If 1996 is a normal year as seasonal hay prices are concerned, then we would normally expect a 20% increase in price from July to December. With $110/ton hay today (or higher), this would indicate a $132 price in December. The break-even storage price for $110 per ton hay for 6 months is $132.05.

This indicates that if we get a normal season price increase in hay, the result is basically the same for selling or storage. The major difference is that the hay producer stands all of the price risk. If hay goes up more than normal, the producer will be rewarded for taking the risk with higher prices; however, if prices do not increase the normal amount, then the producer would have been better off by selling hay in the field today.

Hay Price in the Field July ($/ton)	Storage Period
Hay Price in the Field July ($/ton)	2 Months	4 Months	5 Months	6 Months	9 Months
80	$94.88	$96.22	$96.88	$97.55	$99.55
90	106.05	107.55	108.30	109.05	111.30
100	117.22	118.88	119.72	120.55	123.05
110	128.38	130.22	131.13	132.05	134.80
120	139.55	141.55	142.55	143.55	146.55
130	150.72	152.88	153.97	155.05	158.30
¹Includes 10% shrink, 10% interest on money and $5 per bale loading, hauling, unloading

With the odd weather pattern we have had during the last year, insects are doing things we never expected. Grasshoppers and caterpillars are running rampant in almost all situations, and alfalfa fields are no exceptions.

This is the time to control grasshoppers. Producers should not wait until they are winged and large, when control is difficult or impossible.

Eight or nine adult grasshoppers per square yard should cause alarm to forage producers. Some say that many grasshoppers eat as much as a cow. Grasshopper problems will not go away until hard freezes come in several months.

Grasshoppers normally begin at field edges, and that is the best place to scout and treat when high numbers develop. Treating border areas is much cheaper than treating whole fields.

The following partial list of insecticides may be useful in controlling grasshoppers in areas where the number of small grasshoppers has reached the economic threshold.

Product	Rate per Acre
Malathion	1-1.25
Sevin	1.5
Parathion
(Ethyl or Methyl)	0.5
Cygon or DeFend	0.5
Furadan	0.25

There are many worms, or more correctly, caterpillars, in alfalfa fields this summer. There are more than have been seen in many years, sometimes devastating fields. There have been many questions related to Sampling For Summer Defoliators In Alfalfa

The following is a generalized sampling procedure for various larvae, such as the fall armyworm, corn earworm, beet armyworm, garden webworm, alfalfa webworm, alfalfa caterpillar, and green cloverworm, any or all of which may be in your field this summer.

This sampling method is conducted by use of a standard insect sweep net. Be aware that this method will not be satisfactory when sampling for the army cutworm and the variegated cutworm.

Make 20 sweeps in each of 5 areas of the field. Then count and record the average number of larvae per sweep. Now, measure or estimate the length of typical larvae of each species. To make the survey more meaningful, make a visual estimate of the percentage of defoliation in each area sampled and the percentage of plants showing feeding damage.

It is also important to record any parasitized or diseased larvae of each species. If the number of healthy worms exceeds 5-6 larvae per sweep and defoliation is obvious then controls may be needed. If harvest time is near, haying will destroy most of the larvae and save the time and expense for chemical control.

One of the most frequently asked questions about alfalfa has to do with trying to keep "good alfalfa land" in alfalfa as much as possible.

EXPLANATION: Establishing alfalfa following alfalfa is difficult because of several problems, including:

Many studies indicate that alfalfa can be reestablished successfully following alfalfa. Most reports of problems with autotoxicity are from greenhouse and field studies where top growth of alfalfa was incorporated into the soil and alfalfa replanted immediately. Assuming little foliage was plowed under due to a thin stand, the importance of autotoxicity would be reduced greatly.

Under some circumstances good producers can have success with alfalfa following alfalfa immediately with special attention. These include:

--Plentiful rainfall or irrigation between alfalfa stands can alleviate problems with dry soil profiles.

-- Deep moldboard plowing can assist with removing many of the insects and pathogens from the area where seedlings will grow.

--Application and incorporation of needed fertilizer and lime before planting back to alfalfa can eliminate nutrient deficiencies.

Rotation to other crops allows more time to address these problems. How quickly one can rotate back to alfalfa depends somewhat on weather and how much time is needed to address problems carried-over from previous stand. Currently, at least a 2-year rotation to another crop is recommended. Increasing rotation time between alfalfa stands minimizes most problems.

From the Soon-to-be-Published O.S.U. Extension Circular 949. Alfalfa Stand Establishment Questions and Answers.

Plans are under way for the Alfalfa Expo this fall. It will 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. We need to 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 probably included seed, chemicals, lubricants, etc.

Anyone wanting to donate to the auction should contact one of the Members of the Board(listed on the last page).

The auction last February generated about $18,000. It is planned to have such auctions during the EXPO during the fall each year.

Other activities during the EXPO will be the Cow-Calf Symposium, a hay show, and educational programs. Mark your calendar for October 24 for the EXPO at the Grady Co. Fairgrounds. --

IF YOU ARE PLANNING AN ALFALFA MEETING, CALL AND GIVE US THE DETAILS. WE WOULD LIKE TO INCLUDE IT IN THE LIST.

August 13 Regional Alfalfa Production Meeting. Lincoln, Okfuskee, Creek, Seminole, Pottawatomie, Hughes and other Counties. Meet at the 99^er Restaurant in Prague. Call your county Extension Ag. agent for details.

August 15 Eastern Research Station Tour, near Haskell. Wide variety of forage and row crop topics. Details will follow in the NEWS.

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.

OKLAHOMA ALFALFA

HAY & SEED ASSOCIATION

Volume 20 No. 76 July 1996