Crop Challenges In 2024 Highlight The Continued Need For Research And Development

DR. ADAM FAMOSO

RAYNE, LOUISIANA

The 2024 rice crop in South Louisiana exemplified the ongoing challenges faced by the rice industry. Over the past decade, we have experienced significant fluctuations between "good" and "bad" years, primarily driven by extreme environmental variations in temperature, rainfall, and disease. However, in 2024, these drastic differences manifested within the same growing season. Later-planted rice encountered substantially more issues than rice planted earlier. Surprisingly, much of the later-planted rice was sown within the typically favorable planting window. Meanwhile, earlier-planted rice produced good initial yields that drastically declined due to delays in harvesting caused by persistent rain over a 10-14 day period. Many fields appeared promising and were expected to yield well, but when combines entered the fields, the actual yields were disappointingly low. 

In addition to low field yields, the milling yields were also down, particularly for rice harvested at low moisture levels. Grain moisture levels dropped rapidly in the fields, and persistent rains hindered timely harvesting, resulting in large areas of rice being collected at suboptimal moisture levels. When grain moisture falls too low and is subsequently reabsorbed, it can lead to fissuring – small hairline fractures that increase the risk of breakage during milling. While all rice varieties experience reduced milling yields when harvested at low moisture, the extent of the decline varies significantly by variety. 

There was no single factor that could account for the lower field yields; however, several common challenges emerged. The most prominent issue was disease, with extensive areas affected by sheath blight, Cercospora net blotch on the stem/Cercospora panicle blight, and smut on the grains. Although these diseases negatively impacted yields, they do not fully explain the low output, as many fields experienced late disease development, post-grain filling, and still achieved respectable yields. More consistently observed was the ineffectiveness of fungicides in controlling these diseases, contrasting sharply with their demonstrated efficacy in earlier years. 

Insect pressure was extremely high in 2024, particularly from stemborers, which became prevalent later in the season and in the ratoon crop. Research conducted by the entomology program at HRCRRS over the past few years has shown that the commonly used Dermacor seed treatment has diminished in effectiveness against the rice water weevil. Producers have reported similar reductions in Dermacor's efficacy, especially in water-planted rice. While the treatment still provides a significant positive effect, the damage from insects is substantial enough to result in reduced yields. 

The recent and ongoing challenges faced by the industry underscore the urgent need for research into best practices, the development of varieties that can better withstand current environmental conditions, and the introduction of new crop protection products. 

Although overall field yields have remained relatively stable in recent years, the performance of new rice varieties compared to older ones has significantly improved. For instance, when comparing the most widely grown Clearfield variety from 2024 (CLL19) to the leading variety in 2014 (CL111) across six years and 112 experimental trials, CLL19 achieved a yield that was 12% higher. However, its whole milling yield was 1.5 percentage points lower than that of CL111. A similar trend was observed with the conventional long grain varieties: Avant, the most popular in 2024, outperformed Cheniere from 2014 in yield by over 12% and had an increased ratoon yield but had an average whole milling yield that was 3 percentage points lower. 

The notable improvement in yields from new varieties, paired with stagnant overall field yields, suggests that other factors are constraining yield increases. These factors likely include more extreme and unpredictable environmental conditions, decreased effectiveness of agricultural chemicals, and heightened pest and disease pressures that have emerged recently. 

Addressing these complex issues will not be easy, but they must be confronted. The situation stresses the vital need for ongoing research by universities and private companies to develop new varieties and management strategies. Additionally, it is crucial for new agricultural chemicals to enter the market to help the rice industry maintain its capacity to produce abundant and sustainable crops. Given limited resources, it is essential to concentrate these efforts on the most pressing challenges, prioritizing actions that will produce substantial benefits for the largest number of growers and the industry as a whole.  ∆

DR. ADAM FAMOSO: LSU AgCenter