Occurrence and evaluation of major diseases and insect pests on main sugarcane varieties in medium-term growth peroid in Guangxi

To determe the major diseases and insect pests of sugarcane and the resistance to diseases，the occurrence of major diseases and insect pests on 11 main sugarcane varieties cultivated in 8 producing areas of Guangxi during the medium-term growth peroid in 2015 was investigated，and the resistance to smut and mosaic diseases in the field was evaluated. The results showed that the dead heart rate（ DHR） ranged 0.00%-38.55%，new-planting of Guiliu 2 and ratoon of Liucheng 05-136 varieties were most serious in Beihai city，and the DHR were 38.55% and 37.66%，respectively. Smut disease rate ranged 0.00%-24.89%. sugarcane ratoon was more susceptible than new-planting to smut in all investigated varieties. Variety ROC22 was most susceptible to smut and identified as moderate susceptible. Guiliu 2 was the second susceptible and identified as resistance with smut disease rate 7.45%， and the 9 rest varieties had high resistance. Sugarcane mosaic diseases were mildly occurred in Guangxi，the disease rate ranged 0.39%-7.73%，ROC22，GT42 and Guiliu 2 expressed moderate resistance and the rests exhibited resistance. Sugarcane destroyed seriously in Nanning and Beihai more than other producing areas. The evaluation system of variety resistance to sugarcane borers expected to be constructed. ROC22 was most susceptible to smut，compared with other main varieties. Mosaic diseases were minor in Guangxi. Accurate evaluation of the resistances to smut and mosaic should comprehend the expression of multi-location and multi-year.