P-469 - Hoja Blanca: An Emerging Viral Disease Threatening Rice Production in the United States

Hoja Blanca, caused by the Rice Hoja Blanca Virus (RHBV), is a devastating disease in rice in Central and South America and the Caribbean, causing crop losses of up to 100%. RHBV is solely transmitted by the rice delphacid (Tagosodes orizicolus). In 2024, Hoja Blanca-like symptoms (white leaves, stunted growth, and incomplete grain filling) were observed for the first time in ratoon (2^nd harvest) crops in Texas following outbreaks of rice delphacid. The objectives of this study were to survey disease outbreaks and molecularly identify the pathogen. Surveys were conducted in affected counties in Texas, and symptomatic rice plants and associated rice delphacid insects were sampled. RT-PCR analysis of both plant and insect samples confirmed the presence of RHBV, with gene sequences showing 95 to 99% similarity to viral isolates from Colombia, Costa Rica, and Peru. Hoja Blanca affected nearly 1,000 hectares of rice, including organic rice, in Colorado, Jefferson, Waller, and Wharton counties. RHBV infected almost all rice varieties, including CL153, CLJ01, CLL18, Dixiebelle, Presidio, PVL03, and RT7302 (hybrid), with 5 to 20% of plants showing symptoms. This is the first documented case of the disease in Texas. Hoja Blanca was previously reported in Florida, Louisiana and Mississippi between 1957 to 1959, but it has not been present since. Given the high mobility of the insect vectors, the emergence of this viral disease poses a serious threat to rice production in the U.S.