Wheat leaf rust and stripe rust an emerging problem statewide

While recent rains have been a boon to many crops in the state, they have also presented an unfortunate emerging issue with wheat rust development throughout the state, according to Texas A&M AgriLife Extension Service specialists.

After years of drought, the moisture from recent rains coupled with warm winter temperatures has created conditions for the widespread development of stripe rust.  

“Stripe rust is extensive this year, and we’ve been seeing it in our wheat trial plots and in producers’ fields for the past few weeks,” said Brandon Gerrish, Ph.D., AgriLife Extension statewide small grains specialist in the Department of Soil and Crop Sciences, Bryan-College Station. “Leaf rust came on a little later but has not been as widespread as the stripe rust.”

Gerrish said he and others in the department located throughout the state are continuing to see the development of rusts in many wheat-producing areas and anticipate the rusts will continue to develop and spread if not treated.

“The recent rains have increased the chances of helping maintain good yield potential but have also brought the rust that can detract from higher wheat yields, so it’s a mixed blessing,” he said.

“The majority of growers with a decent wheat crop to protect already have or should be applying fungicide on susceptible wheat varieties.” 

The Rolling Plains have had good moisture and continued rainfall, so that area has been one where the rust problems have been worse, especially with stripe rust, Gerrish said.

“Texas wheat growers are no strangers to rust issues, but it has been a few years since they have had to deal with it, and the extent of the rust we’re seeing this year is more than usual,” he said. 

On the positive side, Gerrish said, because of good growing conditions and more wheat acres planted, overall production for this year is likely on pace to exceed that of previous years.

A statewide prevalence of stripe rust

Emi Kimura, Ph.D., AgriLife Extension agronomist and associate professor in the Department of Soil and Crop Sciences based in Vernon, has been monitoring wheat trial sites and producer fields in the northern Rolling Plains.

“There has been a lot more rust in this area than we’ve seen in the past several years,” Kimura said. “Many producers are actively spraying their fields to control its spread.”

Kimura, who visited both wheat trial sites and producers’ fields, said disease pressure remains high, but there has been no significant additional spreading of rust on the affected wheat. 

“Depending on the wheat varieties, rust pressure differed widely,” she said. “Varieties resistant to rust had a lower rust score, while other varieties susceptible to rust had higher rust scores.”  

Stripe rust also has been prevalent across the southern Rolling Plains and Central Texas, said Reagan Noland, Ph.D., AgriLife Extension agronomist and assistant professor with the department based in San Angelo.

“There has also been some leaf rust reported, but that has not been observed consistently or at levels that are especially concerning,” Noland said. “It looks like untreated fields are beginning to get rust on the flag leaf.”  

A recent rust report summary by experts in the Department of Soil and Crop Sciences focused on the South Texas and Blacklands regions also recognized an increased prevalence of both leaf and stripe rust in those areas.

According to the report, both leaf rust and stripe rust were observed at trial locations in Castroville, where there was high disease pressure. Oat crown rust and stem rust were also observed at that location.

According to the report, while stripe rust was the most prominent disease at the McGregor trial site, leaf rust was expected to develop further as temperatures increase.

Stripe rust was also observed at trial sites in College Station but was not as prevalent as at the McGregor and Castroville sites. Powdery mildew was observed in all three locations but not at what was deemed a serious level.

AgriLife Extension experts will continue to monitor fungal, bacterial, and viral wheat and oat diseases at these sites.

Producer decision-making on wheat 

The variety of wheat a producer plants depends greatly on what the producer plans to do with the crop but can also affect the amount of rust issues seen in their fields.

“Many producers will grow wheat for beef cattle gains or even as cool-season silage for dairy cows,” he said. “Others will grow wheat to sell on the market, but that is greatly influenced by the price of wheat, which is currently fairly low. Producers must decide what is in their best interest economically.”   

He said for wheat ultimately intended for grain production, it is generally a good idea to plant a variety bred for greater rust resistance. Texas A&M AgriLife-bred wheats TAM 115, TAM 116 and TAM 205 are all known for their resistance to leaf, stripe and stem rusts.

“Stripe rust severity varies widely across varieties relative to genetic resistance and fungicide application,” Gerrish said. “Many growers have applied a fungicide to try and curtail the appearance or spread of rust, with the products used ranging from lower-cost treatments that stop the existing rust from progressing to more expensive treatments that also provide some residual protection from further occurrences. The type of treatment also depends on the crop potential, growth stage, degree of rust infection and other factors.” 

More information on wheat varieties can be found in the Texas Small Grains Variety Testing publication.

AgriLife Extension district reporters compiled the following summaries:

Central

Rainfall varied throughout the district, but some counties remained dry with lake levels at 30%. Other counties received heavy rains for up to four days. There were reports of up to 7 inches of rain in some areas, leading to steady runoff, creeks flowing over their banks and full stock tanks. Temperatures remained cool and kept winter grasses green and growing. Bermuda grass was emerging slowly due to cooler weather. Rangeland and pasture conditions were fair to good. Native and improved grasses were greening, but cool nights slowed growth. Producers were spraying weeds and fertilizing fields, and many producers got their first cut of hay. Wheat and oats were being grazed out. Corn planting was wrapping up, and the crop was off to a good start. Some early planted cotton had emerged. Cotton planted in the areas that received heavy rainfall may need to be replanted. Wheat continued to look good. Grain sorghum planting began with some fields remaining to be planted. Most cattle looked good on native pastures, and supplemental feeding slowed. Cattle prices were high, while sheep and goat prices held steady.

Rolling Plains

The Rolling Plains experienced widespread rains totaling 1-3 inches in some places. Wheat was starting to produce grain heads. Farmers were optimistic about the upcoming harvest. Many farmers and ranchers also used some good wheat to swath and bale hay for livestock feed reserves. Cattle on pastureland and wheat were reported to be in better-than-average condition

Coastal Bend

Recent scattered showers aided cotton planting, while recent thunderstorms delivered beneficial rainfall but delayed some crop planting. Weather conditions enabled rapid growth in corn. Cotton emerged well, and rice planting was nearing completion. Corn and rice were reported to be in excellent condition, with some fields undergoing flooding for rice planting. The transition from cool to warm-season perennials was progressing. Producers were actively controlling weeds in fields. Adequate soil moisture maintained excellent rangeland and pasture conditions, allowing for ongoing fertilizer and herbicide applications. Livestock were finding ample feed at most operations despite drying conditions. Pastures were greening up quickly and supporting healthy livestock.

East  

The district received as much as 10 inches of rainfall in some counties. Ponds, creeks, rivers and lakes were overfull. Multiple counties reported flooding. Pasture and rangeland conditions were good to fair. Subsoil conditions were adequate to surplus. Topsoil conditions were surplus. Pastures and hay meadows have been thoroughly saturated, and producers faced difficulty accessing them. Grass and forage growth helped producers extend their hay supplies. Cherokee County reported good numbers and high prices at the cattle market. Most other markets reported a drop in prices. Livestock were in fair to good condition, with some supplementation taking place. Gnat problems have been reported.

South Plains

Rainfall totals ranged from 1-3 inches across the district. Farmers were waiting for specific areas to dry up to prepare for planting. Winter wheat was starting to head out in a few fields, but much of it will take several more weeks. Warm-season grasses in native pastures were beginning to green up slowly. Corn planting started last week. Some wheat fields were being sprayed in preparation for planting. Fields with stubble were being prepared for planting. Farmers were deciding whether to keep their wheat and harvest or spray it. Cattle were in good condition.

Panhandle

Afternoon high temperatures gradually warmed toward the latter part of the week. Rainfall amounts in the area were minimal, and the distribution of precipitation was isolated. Numerous sprinkler pivots were being operated to build soil profile moisture before planting corn, cotton and other warm-season crops. Tillage operations continued across fields and have included the application of immobile nutrients in fertilizers, pre-plant herbicides and possibly insecticides. Cover crops in pivot fields received supplemental irrigation, and some will receive herbicides to terminate growth as spring planting season arrives. More rain was needed for wheat and rangeland to green up. Producers continued supplemental feeding of their herds. Stocker gains were great on wheat due to warm weather. Overall, soil conditions were reported from adequate to short. Pasture and rangelands were reported from fair to very poor. Winter wheat was reported good to poor.

North

Topsoil and subsoil conditions were adequate to surplus across all counties within the region. Pasture and rangeland averages were fair to good and excellent to good for counties in the region. A rain system brought various amounts of rain over the past week, with rainfall from 2-10 inches throughout the region and flooding in some areas. Wheat, oats and forage grasses were all progressing towards maturity. Pecan trees were flowering and setting crops for the year. Many corn fields were standing in water because of the rainfall. Cool temperatures restricted growth in some crops. The spring forage was coming along nicely. Livestock conditions were good, with increased available forage from cool to warm-season forages. Nuisance flies and horn flies were on the rise. Many insect species were emerging.

Far West

Last week was suitable for work, with temperatures ranging from the low 50s to mid-80s. In spite of high winds, no damage was reported. There was little precipitation, and soil moisture levels remained steady, ranging from short to adequate. Evaporation was higher than normal and was removing what little topsoil moisture remained. The heat helped corn, sorghum and melon growth. Irrigation water was still moving decently in the soil; however, with falling capacity and no help from rain, growers were debating how much longer lower-capacity fields could continue production. Livestock continued to be fed as pastures had no grazing. Alfalfa fields were irrigated twice in most areas and should be cut for the first time this season by the end of the month. Pecan orchards were irrigated or were in the process of being irrigated. There was bud-break throughout the valley, indicating the pecan season began. The El Paso valley was fortunate to have a full allotment of water this year. A little wheat was grazed out while a few more fields were baled. The remainder of the irrigated acres will be harvested for grain, mostly for seed for next season. All dryland was being terminated for cotton cover. Livestock were in fair condition. Producers will begin working on lambs soon.

West Central

Severe thunderstorms hit parts of the district with high winds and hail. Temperatures ranged from the upper 60s to lower 90s. Producers cut some small grain fields for hay and increased field preparation for warm-season forage planting. Most pecan trees broke winter dormancy. Many producers were planting Sudan grass. Winter wheat needs moisture within the next week. Stock tanks needed good runoff to fill up before summer arrives. Weed management was an ongoing issue. Pasture and rangeland conditions were declining due to drier weather. Spring cattle work continued; cattle remained in good condition.

Southeast

Rain provided a good amount of water for farmers who had planted. More rain is needed to benefit pastures and rangelands. Wheat continued to do well with the increased rainfall. Producers were preparing cotton. Lingering ryegrass and warm-season forages were beginning to emerge. Most rice looked good. Pecans were in average-to-good condition. The cattle were in good condition.

Southwest

Weather conditions were dry and the wind persisted. There were reports of rain showers, with some areas receiving hail. Overall, some areas received between 1-3 inches of rain. All corn was up, but some damage from hail was reported. The comparatively cool weather was helping to reduce evapotranspiration rates for the growing crops. Some wheat and oats were laid over due to high winds. Irrigated crops looked good. Pastures were green with animals grazing, while other land was tilled and seeded. Only a few pastures were flooded. After the storm, fields required a couple of days to dry before equipment was used on the soil. Pastures and rangeland look good. Producers were heavily supplementing livestock. Beneficial brush was slowly emerging.

South

Weather conditions were mild with scattered thunderstorms. Producers reported an average of 1 inch of rainfall. Wheat crops were reaching maturity and beginning to turn brown. Corn crops continued to progress under irrigation. Citrus trees set their fruit for the year. Cotton planting continued. Pasture and rangeland conditions were slowly improving with increased moisture. Hay fields were under irrigation as producers prepared for the next cutting. Pasture availability was good, but supplemental feeding continued for all livestock. Most cattle have improved body scores this spring, and calves were growing nicely. Cattle sales slowed the last few weeks due to weaker prices and above-average grazing conditions. Wildlife were thriving with the excellent rangeland and pasture conditions this spring.