Story and photos by Derek Albert
CROWLEY, La. – As Louisiana approaches summer, warmer temperatures and afternoon showers are nudging the state’s 2023 rice crop closer toward harvest.
LSU AgCenter rice specialist Ronnie Levy said rice growers are scouting their crops for diseases as the current warm and wet weather patterns allow fungal diseases such as blast and cercosperaq to propagate.
“It’s still early in the season, but we’re starting to see a little bit of disease showing up,” Levy said. “With the weather we are starting to have, it is something we have to be concerned about.”
Rice growth was slowed a bit earlier in the season because of cooler temperatures, Levy said. But beneficial weather patterns have allowed the early-planted crop to catch up.
“We started off everything when it was cold, and it really grew slow. A lot of the early rice was way behind,” Levy recalled. “Now, with the better weather conditions that we have had for the last few weeks, we saw a vast improvement of rice in the fields. Tillering was good. Growth was good. The fertility appeared to really be moving the rice forward.”
The rice plant’s ability to produce grain is highly dependent on warm, sunny weather conditions, Levy said.
“The rains keep the weather cooler--which helps with respiration of the rice plant, but it also increases the potential for disease,” Levy said. “Those rains keep the plants wet longer during the day, and really aid in some of these diseases really blowing up in the fields--which can reduce yields significantly.”
AgCenter rice pathologist Felipe Dalla Lana corroborated Levy’s concerns about the emergence of disease in rice fields as precipitation increases across Louisiana. He said the month of June marks a critical point in the season where disease becomes evident. Late-planted fields will be more susceptible to cercospera and blast, he said.
“We have started to see sheath blight develop in the field,” he said. “We are starting to see some blast and cercospera. Right now, is a key moment for decision making.”
Dalla Lana said farmers may not have a plethora of options for fungicide treatments, but there are a few that have proven to be effective. For treating sheath blight, he recommends using fungicides that contain Azoxystrobin.
Dalla Lana said the Rice Pathology Project is currently monitoring 60 different field trials for a host of pathological studies. Some of those trials include multi-location cercospera field trials.
“We understand that cercospera was a huge problem last year, but it is a disease that does not occur every year,” he said. “We hope with the six trials across different environments, we are able to capture some of the important information that we need to control cercospera.”
While three of these trials are located at the H. Rouse Caffey Rice Research Station, there are two at the AgCenter’s Macon Ridge Research Station in Winnsboro. Another is a bit further away.
“We have this trial in Arkansas in collaboration with pathology there,” Dalla Lana said. “We expect that this partnership with the University of Arkansas will continue for many years. Eventually, we will also host some studies from Arkansas here at LSU.”
AgCenter Rice Agronomist Irish Pabuayon said the early-season cool temperatures and frequent rains may have delayed the growth of some varieties that were not able to get the right amount of sunlight needed for optimal growth. Another current challenge that Pabuayon said she is seeing in farmers’ fields has researchers a bit puzzled.
“We have some lines from other companies that we are seeing some yellowing on top of the leaves,” she said. “We are not sure at this time if this is somewhat related to nutrient deficiency, or a disease or something that we don’t know at this time. So. We are doing some analysis on nutrient deficiency and then we will go from there.”
AgCenter rice weed specialist Connor Webster said weed pressures are becoming evident right now, especially in the form of the easily misidentified fimbristylis. The yield-robbing weed resembles rice flatsedge when it is small, but fimbystlis is really flat versus the three-sided rice flatsedge, Webster said.
“We are seeing a lot of fimbristylis start to poke though that people may have missed with early applications,” Webster said. “They may have misidentified it or used something, and the fibrystlis was a little too big and it started regrowing. So, we’re kind of in a salvage situation.”
The Rice Weed Science Project is currently honing its focus into NewPath carryover. Webster explained that he and his team are analyzing farmer-provided soil samples to simulate the levels of the active ingredient Imazethapyr.
“We are trying to use low rates of NewPath to mimic the certain amounts of NewPath that we are finding in the soil affecting rice from previous years,” Webster said. “We’re seeing what that is doing to different varieties in terms of yield.”
LSU AgCenter entomologist Blake Wilson said—so far this growing season—insect pressures in rice fields have been minimal. There were some instances of rice black bug (Amaurochrous dubius). These pests can feed on the leaf sheath causing dead or dying leaves, usually lower leaves, in otherwise healthy rice. He said there have been a few instances of apple snails damaging rice fields that are in a rice and crawfish rotation. Wilson said seed treatment for pest control is the best course of action, but it is not always a panacea.
“I encourage people to check on the health of their rice because we had some seed treatment control failures in late planted rice last year,” Wilson said.
The AgCenter is offering a glimpse of a number of the field trials referenced above at a pair of field days scheduled for later this month. First, on Wednesday, June 14, Acadia Parish Extension Agent Jeremy Hebert and Connor Webster are hosting their annual Acadia Parish Rice Field Day at the Rice Research Station’s South Farm. On display will be several herbicide efficacy trials. Then, on Wednesday, June 28, the H. Rouse Caffey Rice Research Station will be hosting its 114th Rice Field Day where AgCenter rice researchers will share the latest developments in rice production research.