July 2009 Archives

The East Texas Chapter of the Texas Master Naturalist, a volunteer service organization dedicated to providing education, outreach, and service for the beneficial management of natural resources and natural areas, is seeking applicants for their fall 2009 training class set to begin September 10.

For more information or to obtain an application packet, please visit the chapter's web site at http://woodduck.org or call Brian Triplett at 903-590-2980 or Irene Hamel at 903-566-9394.

The very dry summer conditions we have been experiencing are prime grasshopper growing weather. I am getting spotty reports of heavy 'hopper infestations in southeast and western parts of the county. The grasshoppers are already mature and flying, which makes them more mobile. The ones I have personally seen seem to be the differential grasshopper, which is one of the most destructive to crops/pasture land of the 'big five' species of grasshoppers of economic importance found in the state.

If you have been on the receiving end of this rainfall of late, I want to tell you to be on the lookout for Fall Armyworms in the near future. To a pregnant armyworm moth flying north from drought-ridden central Texas, our area is going to look like an oasis, prime territory to lay her eggs. I have already heard reports of Fall Armyworms near Sulphur Springs so I think it is just a matter of time before we have them in our area too.

If you have grasshoppers, the economic threshold of treatment is more than 8 grasshoppers per square yard (or as I like to say, 1 per square foot). Anything above 1 per square foot means that the 'hoppers are consuming more dollars worth of forage than it would cost in insecticide to treat them. The good news is that we typically see only one generation of grasshoppers per year.

If you find yourself with Fall Armyworms, the economic threshold of treatment is more than 3 young armyworms per square foot. If you have more forage than you need (which is unlikely) then you should probably consider skipping the cost of the treatment. However, if you have fertilized warm season pastures and are awaiting another hay cutting, treat if the armyworm load climbs above 3 per square foot. If you plant winter pastures, definitely treat when numbers justify as these insect pests can have more than one generation per year in our area and just might stick around until first frost if weather conditions are favorable to their continued development.

Please note that trade names and retail prices listed below are for educational purposes only and that no specific endorsement of any product is intended or implied.  Please note that there are also waiting periods for some products listed below that are required between application and grazing / cutting for hay.  Follow all label directions and wear required personal protective equipment when handling pesticides and making pesticide applications.

Grasshopper Control Options:

Sevin, Malation, Mustang Max, & Dimilin (Too late for '09 as 'hoppers are past 3rd instar)

Armyworm Control Options:

Sevin (Carbaryl 4F), Mustang Max, Malathion 5EC, Methomyl (Lannate VL), Methyl parathion 4E, Tracer 4SC, & Intrepid 2F

Fact Sheets (Please defer to pesticide list above for differences between pesticides listed on site and those mentioned in the fact sheets):

Grasshoppers grasshoppers.pdf (2 MB)

Armyworms ArmywormFactSheet2008.pdf

During droughty conditions, certain forage species that we feed livestock may become unsafe for animal consumption.  Two problems that producers might face during these dry weather patterns are nitrate accumulation and prussic acid formation.

Nitrate Accumulation - Regardless of the form of nitrogen applied via fertlizer (ammonium or urea) the form of nitrogen primarily taken up by plants is nitrate.  Soil microorganisms convert ammonium nitrogen to nitrate nitrogen.  Nitrates are extremely soluble in water and are easy absorbed by plant roots along with moisture in the soil.

Three conidtions that cause nitrate accumulation:

1. During times of high temperatures and adequate soil moisture, plants can undergo a process called photorespiration during which carbon dioxide is released into the atmosphere rather than being stored in the plants as a carbohydrate.

2. When the soil contains nitrate nitrogen but little soil moisture, nitrates beome highly concentrated in the water that plants take up.

3. Herbicide injury can limit the conversion and assimilation of nitrates in plants.

Some common forages that can accumulate toxic levels of nitrates include:  barley, corn, flax, millet, sudangrass, and johnsongrass.

Prussic acid in forages can also pose a threat to animals.  Prussic acid can build up in plants during the following 5 conditions:

1. Grazing conditions are poor and stems do not develop properly.

2. Recent hay harves or grazing causes slow and stunted growth of new plant tissue.

3. Nitrogen fertilizers are over-used or there are other soil fertility or nutrient imbalances.

4. Plants develop new growth after prolonged drought.

5. Plants are injured by herbicides, frost, hailr, or other events. 

The list of forages that can accumulate prussic acid include:  pearl and foxtail millet, sudangrass and sudangrass hybrids, sorghum-sudangrass hybrids, johnsongrass, and grain sorghum.

Two laboratories located on the campus of Texas A&M University can analyze forage or other plant samples for nitrates and prussic acid.  It is best to send samples of suspected forages to these labs via UPS, FedEx or LoneStar to ensure they arrive directly at the lab of choice as quickly as possible.  The Texas AgriLife Extension Service Soil, Water, and Forage Testing Laboratory can be reached at 979-845-4816.  The Texas Veterinary Medical Diagnostic Laboratory can be reached at 979-845-3414.  Call either lab to determine the best way to collect and submit your sample.

Do not feed any suspect forages or plants to livestock until you receive your results and are presented with feeding recommendations from the lab.

For more information on these two problems, read this publication (E-543) "Nitrates and Prussic Acid in Forages: Sampling, Testing, and Management Strategies" by Provin and Pitt.  e-543 nitates and prussic acid in forages.pdf