Locoweed: A Natural Disaster

andBIOSECURITY RISK

David GrahamAgricultural Extension AgentNew Mexico State University

Cooperative Extension ServiceUnion County New Mexico

Locoweeds and Milkvetches“A Bio-Security Issue???” Biosecurity is the policies and measures taken to protect from

biological harm. It encompasses the prevention and mitigation from diseases, pests, and bioterrorism, of the following area:

economy environment public health which includes food and water supply, agricultural resources

and production, pollution management, blood and blood product supplies Biosecurity warrantly attempts to ensure that ecologies sustaining either people or animals are maintained. This may include natural habitats as well as shelter, productive enterprises and services, and deals with threats such as biological warfare or epidemics. This is related to the more passive concept of biosafety.

Locoweeds and Milkvetches“A Bio-Security Issue???”

Bio-security issue is an integral part of any agricultural emergency response plan.

An accepted definition of an agricultural emergency is “ any incident having a negative impact on agriculture, including any outbreak of disease, or natural or man-made emergency that could result in economic or human losses”.

Locoweeds and Milkvetches“A Bio-Security Issue???”

THE ANSWER IS YES. SO --- WHO CARES?WE SHOULD: IF WE DEVELOP AN AGRICULTURAL

ANNEX TO OUR COUNTY EMERGENCY PLANS, WE CAN INCLUDE MITIGATION AND PLANS FOR LOCOWEED INVASIONS EQUAL TO OTHER EMERGENCIES.

Common Locoweeds and Milkvetches of New Mexico

OXYTROPIS: “CRAZYWEEDS”

ASTRAGALUS: “LOCO or MILKVETCHES”

Oxytropis lambertii, sericea

Common Locoweeds and Milkvetches of New Mexico

Astragalus agrestis, allochrous, amphioxys,

bisulcatus.ceramicus, crassicarpus, drummondii, emoryanus, humistratus, lentiginosus, lonchocarpus, missouriensis, mollissimus, nuttallianus, praelongus,pubentissimus,pracemosus, tephrodes,tompsonii, wootoni

Oxytropis lambertii

CERTAIN SPECIES ARE SIGNIFICANTLY RESPONSIBLE FOR ECONOMIC LOSSES

Oxytropis sericea

“WHITE LOCOWEED”

Astragalus Mollissimus

“PURPLE LOCOWEED”

CERTAIN SPECIES ARE SIGNIFICANTLY RESPONSIBLE FOR ECONOMIC LOSSES

Astragalus emoryanus “Red Stem Peavine”

Astragalus Wootoni “Garbancillo”or

“Rattleweed”

Research Challenges

Localisms and pre conceived ideas. Mineral and feed salesmen.

Old and outdated information.

INTERNET & JUNK SCIENCE

SWAINSONINE

Although the toxin content of locoweeds is not very high—generally less than 0.2% of the plant’s dry weight—it appears to be highest in the flowers and seeds. However, because of its exceptional potency, it has been calculated that levels as low as 0.001% can cause poisoning.

THE ENDOPHYTE

Swainsonine is known to be produced by some fungi, including a plant pathogen and an insect pathogen.

Also, some forage plants are poisonous due to toxins produced by fungi living between the plant’s cells (endophytes). Festucosis, for instance, is a result of toxins in this case “swainsonine”

SWAINSONINE con’t

The chemical structure of swainsonine is not complex and is quite similar to simple sugars, such as mannose and glucose, which it appears to mimic. As a result of this imitation, it stops the action of the enzyme a-mannosidase, which is essential for the proper functioning of all animal cells.

SWAINSONINE con’t

We know that the water soluble “swainsonine” is dispersed very rapidly into the animal body.

We know that its influences are seen in:1. The Reproductive System

2. The Circulatory System and organs

3. The Nervous System.

SWAINSONINE con’t We know that the “swainsonine” makes its

rounds and is eliminated within 48 hours through the urine and the milk in lactating animals.

We know that when animals are removed from access to “swainsonine”, the cells recover in the same order they became damaged.1. The Reproductive System2. The Circulatory System and Organs (immune system)3. The Nervous System (This system does not heal)

ECOLOGY ANDPHYSIOLOGY

When the rain falls may affect locoweed density (Dec. Jan. Feb. some influence, Mar. Apr. May consistent influence, June, July, Aug. NO influence, Sept. Oct. Nov. NO influence)

Drought-stressed locoweed contains more swainsonine

Swainsonine content is a direct result of fungi infecting locoweed

Swainsonine content varies from plant to plant, leaf to leaf on same plant.

MANAGEMENT

BIOLOGICALCONTROL

BYINSECT

FOUR-LINED LOCOWEED WEEVIL Four-lined locoweed weevil

(Cleonidius trivittatus) is the most important insect to attack woolly locoweed. The adults (fig. 1a) are grayish to brownish and about 1/2 to 1 inch long with 4 dark stripes down their backs. They feed on the leaves and stems of locoweed; however, the immature larvae cause most of the damage. Larvae (fig. 1b) are 1/8 to ¾ inch long, legless, cream colored, “C” shaped with a brown head and jaws. They can be found feeding on the outside or inside of the root of woolly locoweed.

FOUR-LINED LOCOWEED WEEVIL

Weevil larvae construct a chamber inside the root or in the soil adjacent to the root in which they pupate (fig 1c). Adults lay individual, bright yellow eggs (fig. 1d) in the late fall through early spring, that are commonly covered with chewed locoweed leaves.

Feeding by two weevil larvae killed most sizes of woolly locoweed in our research plots.

NEW RESEARCH NOW SHOWS

Dr. David Thompson and Kevin Gardner 2008

PLANT STRESS CAUSED BY INSECT ACTIVITY DOES NOT AFFECT THE SWAINSONINE

CONCENTRATION

MANAGEMENT

RANGE AND LIVESTOCK

MANAGEMENT

ANIMALS AFFECTED BY LOCO TOXICITY

ALL ANIMALS ARE AFFECTED, BUT METABOLISM DETERMINES THE EXTENT AND SEVERITY

HORSESELKCATTLE, SHEEPDEERPRONGHORN ANTELOPE

ANIMALS AFFECTED BY LOCO TOXICITY

WHY DO THEY EAT LOCOWEED?

WE DON’T KNOWSMALL % ARE PRONE TO

EAT LOCOWEEDSOCIAL FACILITATION!!!!!!

ANIMALS AFFECTED BY LOCO TOXICITY

BREED DIFFERENCES?

INDIVIDUAL ANIMALS

SOCIAL FACILITATION

Reducing Locoism with MANAGEMENT

Old recommendations that we think are not valid. 1. Graze animals that are familiar with the range. This is probably

counterproductive, because cattle learn to eat plants, especially locoweed, from older, more experienced animals. This behavior often is called social facilitation, or “peer pressure.” Naive cattle that have never grazed locoweed are a safer bet.

2. Don’t graze wheat pasture cattle on locoweed rangeland. This old recommendation assumes that cattle coming off wheat are more likely to graze green plants such as locoweed. Research conducted during this project found no difference in locoism incidence between wheat pasture cattle and native range cattle. All cattle prefer green locoweed to brown grass. Wheat pasture cattle are no more likely to graze locoweed than other cattle.

3. Supplement animals with protein, plenty of salt and minerals. The idea that cattle are more likely to graze locoweed if deprived of salt and minerals, or short on protein, is not conclusive. We highly recommend range livestock receive good mineral, protein, and energy supplements when vegetation warrants supplementation. However, the only way a supplement will reduce locoism is if it prevents cattle from grazing locoweed. Thus far, no such supplement exists.

Reducing Locoismwith Management

Options that have been proven to reduce locoism. 1. Create locoweed-free areas. It would be nice to be able to spray the entire

ranch. However, this is not economically feasible for everyone and may not be necessary. Creating pastures that are free of locoweed provides greater management flexibility when a “safe” area is needed.

2. Observation. Removing cattle that are observed eating locoweed provides relief to the animals and also prevents them from teaching other cattle to eat locoweed.

3. Range readiness. Don’t graze locoweed-infested pastures until warm season grass has started growing. This date varies from year to year, but by June 1, warm-season grasses should provide enough green feed to keep cattle from searching for locoweed. The other danger period is in the fall, when grasses start curing and locoweed once again becomes a preferred plant.

4. Cyclic grazing. Grazing locoweed-infested pastures for less than 4 weeks followed by grazing a locoweed-free pasture for 4 to 6 weeks may avoid the need to totally abandon locoweed pastures.(May work for yearlings)

5. Rotational grazing. Graze the locoweed-infested pastures during the “safe” period (June to September) and the locoweed-free pastures prior to June and after September. Remember, these dates are only guidelines and you will need to spend some time observing cattle grazing locoweed-infested pastures to determine when they quit locoweed and when they start grazing it again.

Reducing Locoismwith Management

6. Flash grazing. Naive cattle normally will not graze locoweed until grazing pressure forces them to eat the plant. A series of trials were conducted near Des Moines, N.M. In the first trial, naive yearling cattle did not graze locoweed until grass use was heavy. In the second trial, the same cattle started eating locoweed when grass use was light to moderate. By the third trial, the same yearlings ate locoweed first and preferred it to other plants. Therefore, we recommend that grass use never be heavy or severe in order to prevent cattle from learning to eat locoweed.

7. Culling. Locoweed affects reproductive performance. Cows that are open in the fall need to be culled, because they “MAYBE” have eaten locoweed and need to be sold. Culling open cows makes economic sense and also has proven to reduce the number of locoweed eaters on the ranch.

8. Aversion. Although this option is still experimental, we believe it offers a lot of promise for reducing locoism. Cattle have been trained to avoid eating locoweed through a process of conditioned food aversion. Cattle are fed locoweed, then dosed with an emetic, lithium chloride (LiCl), to induce gastrointestinal distress. The cattle associate locoweed’s taste with a belly ache and avoid grazing it. Aversion training works best on naive cattle not familiar with locoweed. Steers familiar with locoweed require several doses. Dosage rate is critical, with 200 mg LiC1 per kg body weight being the most effective. Averted cattle must then be kept away from non averted locoweed eaters to prevent peer pressure or “social facilitation” from negating the aversion. This suggests the idea of averting replacement heifers so that their offspring will never be taught to eat locoweed.

Effects on Pregnancy

LOCO WEED EFFECT ON PREGNANT COWS Dr. K.E. Panter USDA/ARS Poison Plant Lab: Cattle graze loco 10 to 14 days during Pregnancy: Pregnancy 0-25 days Cows return to estrus Pregnancy 25-60 days Cows reabsorbing of fetus (usually no sign), with

light grazing may have full term births with weak calves or sick calves. Pregnancy 60-120 days Abortion (may find fetus in pasture), some may

reabsorb fetus. May have cows with hydropsy. With light grazing may have full term births with weak or sick calves.

Pregnancy 120-280 days Weak calves, poor nursing ability, deformed calves, may be fully developed fetal abortion or “still” birth, and if calves live, they will be chronics and poor doers.

There is no quantification to amount of swainsonine ingested or any correlation of swainsonine ingestion and fetal condition.

May see pneumonia in cattle linked to damage to the immune system. May see un-related illness in new born because of immune system damage.

Reducing Locoismwith Management

REDUCE OR ELIMINATE STRESS: Physical Stress Nutritional Stress 1. Supplement correctly (range monitoring)

2. Don’t turn out hungry animals

• OBSERVE, OBSERVE, OBSERVE

MANAGEMENT

USING HERBICIDES

TO CONTROL LOCOWEED

CONTROLLING LOCO WITH HERBICIDES

Locoweed can be controlled at all growth stages by several different herbicides. It pays to spray under ideal weather conditions and shop for the best herbicide price.

Comparison of herbicides Astragalus control

Growth StageHerbicide Dosage(Per./ac) Spring Bloom FallPicloram 0.25 lb. E E EPicloram 0.375 lb E E EPicloram + 2-4-D(1:4) 0.94 lb. E E EMetsulfuron 0.1875 oz/ac F E EMetsulfuron 0.375 oz/ac F E E2-4-D 4.0 lb. F F F

E = Excellent G = Good F = Fair P = Poor

Controlling Locoweed with Herbicides

Additives increase herbicide uptake by locoweed regardless of leaf hair architecture.

Locoweed Herbicide Uptake after 24 Hr. Species Picloram Ally Purple Locoweed 8.9% alone 15.3% alone 83.4% With Diesel 47.3% With Diesel

White Locoweed 11.8% alone 14.5% alone 81.4% With Diesel 79.9% With Diesel

Diesel added at Approximately 15% by volume

This publication isOut of print but canBe viewed & copied athttp://cahe.nmsu.edu

PUBLISHED IN 1999 NMSU

WHERE ARE WE ON LOCO RESEARCH? WE THINK

ANIMALS START EATING LOCOWEED BECAUSE OF A NUTRITIONAL NEED.

OR SOME AS A CURIOSITY

AND HORSES??? BOREDOM THEN SOCIAL FACILITATION KICKS IN.

SOME THINGS WE BELIEVE BASED ONOBSERVATIONS AND EXPERIENCE

RANGE READY LOWER STRESS PHYSICAL & NUTRITIONAL

SUPPLEMENTS ONLY WHAT IS NEEDED

FEED GROUNDS MONITORING AVERSION TURN OUT FULL NEW ANIMALS

THE ONLY THING WE KNOWN FOR CERTAIN

IN LOCOWEED

THERE IS NO

EASY BUTTON