Assessment of inoculation techniques for screening for resistance to red stripe disease.

BERTANI RP; JOYA CM; HENRIQUEZ DD; PERERA MF; CUENYA MI

San Miguel de Tucumán

Congreso; XXX ISSCT Congress; 2019

Red stripe (Acidovorax avenae) is one of the main bacterial diseases that affects sugarcane inTucumán, Argentina. This disease has become important in our country due to its highincidence over the past 10 years. Host-plant resistance is the most effective method fordisease control and breeding programs require effective screening techniques to selectsugarcane genotypes resistant to A. avenae. The aim of this study was to optimize a practicalmethod that simulates natural disease spread and allows reproducible expression of red stripesymptoms. Three inoculation techniques (spraying the bacterial suspension after rubbing theleaf surfaces using refined sand or cotton, and spraying without making a wound) were testedunder controlled conditions. Relative humidity, soil composition and fertilization were optimizedto maximize symptom expression. All methods tested reproduced typical disease symptoms;however, the mechanical inoculation based on rubbing both leaf surfaces with refined sand wasthe most aggressive. The no-abrasion method simulates natural infection conditions, where thedispersion of A. avenae is by wind and rain and is the method that is the most effective in abreeding program for disease-resistance screening. These results represent a valuablecontribution for sugarcane breeding programs that evaluates red stripe resistance of theirmaterial.