The seed and seedling disease complex affecting cotton is of major importance and causes serious damage to the crop. High quality seed is a key component for a successful cotton crop. High quality seed and their resulting vigorous seedlings are tolerant to early season low temperature and less susceptible to seedling pathogens. Susceptibility to the seed-seedling disease complex increases with increased deterioration of seed. Reliable laboratory tests that correlate well with field performance under different planting conditions are needed to monitor and evaluate seed quality. The objective of this study was to evaluate the applicability of methanol stress for cottonseed deterioration, vigor and seed quality testing, and predicting field stand.

Experiments were conducted in 1986 and 1987 to evaluate the performance of cottonseed and seedlings in the laboratory and in the field. The soaking time required to achieve the conditioning and deterioration level of cottonseed was determined. Four methanol treatments and eight cotton cultivars were used. Cottonseed for the eight cultivars, obtained from seed lots with equal seed history, were immersed in 20% methanol-water solution (v/v) for 0 (control) , 1, 3, and 6 hours (hr) . A factorial experiment with eight replications was conducted under controlled soil temperature at 18C in a water bath temperature tank, to evaluate host reaction to Pythium ultimum and Rhizoctonia solani, separately. Field performance of cultivars as affected by methanol treatment was evaluated in College Station over two years.

In laboratory and field tests in 1986 and 1987, seed-seedling disease incidence increased, and germination, emergence, and stand decreased as exposure time to 20% methanol increased from 0 to 6 hr. Methanol treatment for 6 hr reduced stand by 25% as compared to the control, and 20% compared to the 1 hr treatment. The 3 hr treatment reduced stand by 14.7% as compared to the control, and 9% compared to 1 hr treatment. The effects of methanol on disease incidence were more pronounced with Pythium ultimum than with Rhizoctonia solani. Treatment of cottonseed with methanol for 6 hr significantly reduced seedling emergence and final stand under field conditions for all cultivars. Field results correlated positively with those obtained in the laboratory and controlled soil temperature experiments. Methanol stress simulates the effects of field weathering relative to seed deterioration, germination, reaction to seed-seedling pathogens, and stand establishment. Immersing cottonseed in 20% methanol for 6 hr is a reliable technique to alter seed viability and vigor, and may prove useful in predicting potential field performance.