VATIS UPDATE Article

A team of researchers from Kansas State University (KSU), the United States, and Missssippi State University (MSU), the United States, the application of Sulfuryl fluoride (SF) under high temperatures to determine the highest temperature, shortest exposure time, and lowest concentration by time product, the CTP, of SF that can control all life stages of T. putrescentiae. Mobile stages of mites and eggs were prepared in separate ventilated glass vials. Mites were exposed to SF at 1400 gh.m–3 and four high temperature treatments for two days.

Results showed that complete control of ham mites was achieved at 40oC, which was the highest tested temperature. Mites were then exposed to at 1400 gh.m–3 of SF at 40oC for different lengths of time and results indicated that more than one day exposure was required to kill mobile stages and eggs. When mites were exposed to 300 and 1000 gh.m–3 CTP of SF for various exposure times at 40oC, results indicated that mobile stages were 100% killed after 36 h or longer at 300 gh.m–3 and the same result was achieved at 3 h or longer at 1000 gh.m–3.

Egg mortality at 300 gh.m–3 was recorded as 98.9% after 96 h and was 97.8% after 48 h when exposed to 1000 gh.m–3. This study showed that utilizing heat while applying SF at a concentration near the maximum allowable rate to control ham mites will increase the efficacy of fumigant against the most tolerant life stage, the egg. However, when the target CTP of SF was either 300 gh.m–3 or 1000 gh.m–3 at longer exposure times, mortality did not reach the same level found with 1400 gh.m–3.