You Still Have Time! "Pest Management News" is a newsletter which provides timely, accurate and pertinent information in the areas of crop production within the southern rolling plains. Newsletters are written weekly during the growing season and a total of fourteen were issued in 2000. This newsletter will keep you abreast of current insect pest populations, natural enemies, biological and cultural control tactics and chemical control options. It will also provide the user with economic thresholds and other management tools to assist the farm operator in making management decisions. Currently, there is a $10 subscription fee to cover the cost of postage. If you are interested in receiving this newsletter during 2001, please send $10 to

"Pest Management News," P.O. Box 658, Ballinger, Tx 76821, payable to "Pest Management News" by April 16, 2001. There is still plenty of time to send in for your subscription.

Moisture conditions continue to improve going into the growing season. Underground moisture throughout most of the Concho Valley is in very good shape. The Concho Valley Cotton Conference, held on March 27, was a wonderful success. I think everyone present felt the speakers did an excellent job providing pertinent information on the topics discussed during the day long event. More than 375 individuals were in attendance.

With the damp, cloudy weather conditions we have had the past month, leaf rust has exploded across the area. Many fields have signs of rust and these problems continue to increase. Rust is most prevalent on wheat but can also be found on oats.

Rust is a fungi that appears on the plant surface. Fungi are tiny, threadlike microscopic plants, commonly called molds. They require a source of energy, but unlike green plants, cannot use energy from the sun to make food. They must get food from other sources such as the wheat plant. When these plant-feeding fungus types become numerous, a disease epidemic develops. The infection element of the leaf and stem fungi is capable of penetrating into a plant directly and will enter through the plant breathing pores or wounds. Plants have many microscopic breathing pores called stomates on the surface of the leaves. This is a common spot of infestation. Once the fungal infestation element becomes established inside the plant, numerous strands of hyphae start growing and feeding in the plant tissues. Invaded tissue gradually dies as the fungus feeds on it.

Leaf Rust
Leaf rust pustules (uredia) develop primarily on the upper surface of leaf blades. Pustules are round to oval, about 1/50 inch in diameter, light red, and filled with spores (urediospores). These spores are easily dislodged by the wind or rubbing and accumulate as red dust on hands, clothing and machinery. Rust increases water loss from leaves so they die prematurely.

The optimum temperature for sporulation and infestation is approximately 70° Fahrenheit (F) and infestation can occur within four hours if leaves are wet. New pustules erupt within to seven to ten days. Rust development is slowed drastically with cooler temperatures or a shorter leaf wetting period. At 60° F a wetting period of eight to ten hours is necessary. Very wet conditions reduce spore dispersal. Epidemics generally develop when favorable moisture exists and temperatures are above 60° F.

Since the leaf rust loss results from the
early kill of the upper two wheat leaves, the faster an epidemic develops the greater the loss. Loss can be roughly predicted by matching severity on the flag leaf growth stage. If the flag leaf is severely damaged prior to the milk stage, the approximate loss in yield is 25 to 40 percent. If the disease damages the flag leaf between the soft and hard dough stages of the developing wheat yield losses are usually less than 10 percent.

Stem Rust
Stem rust pustules (uredia) develop on leaves, especially on leaf sheaths, necks, glumes and awns. These pustules are 1/16 to 1/4 inch, much larger than leaf rust, dark red in color, considerably longer than wide, and are often evident on both the upper and lower leaf surfaces. Pustules raise and break the epidermis making them rough to touch. As the wheat matures the pustules turn black and remain rough.

Stem rust greatly increases water loss
from leaves and stems so they die prematurely. Shriveled, light weight grain results. Wheat is its most common host, but will attack barley, rye, oats, goat grass and wild barley. With the use of early maturing wheat varieties and resistant varieties stem rust has been reduced to a minor disease.

2

The optimum temperature for sporulation and infestation is approximately 75° Fahrenheit (F) and
infestation can occur within four hours if leaves are wet. New pustules erupt within seven to ten days. Rust development is slowed drastically with cooler temperatures or a shorter leaf wetting period.

Chemical Control
Under severe disease situations, the use of chemical control in conjunction with cultivar resistance may prolong the useful life of that particular cultivar. Several fungicides may be used to control diseases that have reached economic threshold levels.

The mancozeb-containing fungicides (Dithane, Manzate, and Penncozeb) are protectants. They must be in place prior to infection to achieve control. Mancozeb does not enter the plant, but provides a protective barrier to the disease causing organism.

Since most of our wheat has leaf rust already, the fungicides of choice would be Stratego, Tilt or Quadris, which are systemic fungicides. These fungicides enter the plant and move systemically to some degree within the conductive tissues. They may be protective, eradicant, or both. The eradicative properties can stop disease development even though infestations have already occurred; however, symptoms remain if present at the time of the fungicide application. When control of a disease complex is needed, a mixture of a protectant and an eradicant fungicide may be required.

NOTE: With the current price of wheat it may be difficult to justify the application of fungicides, even with potential yield decreases caused by the rust infestations.

NOTE: Be sure to follow label directions. Use on approved crops to control listed pests that have been identified above economic threshold levels.

April 12, 2001
Risk Management Workshop
7:25a.m.-10:00a.m.
St. Ambrose Fellowship Hall in Wall, Texas
The program will include an Ag Marketing Network Teleconference followed by a presentation
by Dr. Jason Johnson-Extension Economist. The workshop is designed to assist producers in developing marketing strategies that will reduce risk and improve profitability. For more information, contact Marvin Ensor at 915-659-6523.

April 24, 2001
Pond Management Seminar
9:00a.m.-12:00p.m. (noon fish fry meal)
Ballinger City Park
The Runnels County Extension Service in cooperation with the Runnels Soil and Water
Conservation District will sponsor a Pond Management Seminar to be held on Tuesday, April 24. The seminar will be held at the Ballinger City Park beginning 9:00a.m. and concluding at 12:00 noon with a fish fry meal.

The program will begin with a presentation on "Aquatic Weeds" by Steve Nelle, NRCS Biologist. Dr. Allan McGinty, TAES Range Specialist, will discuss "Water Management" strategies to increase water capture in ponds and tanks. The last presentation will be "Stocking Farm Ponds and Tanks" by Harold Arms. Three hours of continuing education credits will be offered to pesticide applicators in attendance.

The Runnels Soil and Water Conservation District will also be taking fish orders during the program. Cost of the program will be $5.00 per person and interested persons should contact the Extension Office and 915-365-2219 or the NRCS Office at 915-365-3415 to RSVP by Friday, April 20.

Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.