SUGARCANE DETERIORATION CAUSED BY Diatraea saccharalis IN TUCUMÁN, ARGENTINA

A. R. SALVATORE,; M. L. DEL P. PEREZ; ISAS M; ROMERO E; ZOSSI,; E. WILLINK; GASTAMINZA G.

Workshop; XI Taller Mundial de Fitopatología y IX de Entomología de Caña de Azúcar; 2015

The sugarcane borer, Diatraea saccharalis, is the main sugarcane pest in NW Argentina, especially in Tucumán province where it causes great losses. The galleries produced by the larvae as they bore into the stalks are also the gateway to pathogens such as Leuconostoc mesenteroides, which causes cane quality deterioration. These bacteria produce dextran, polysaccharides and mannitol (a polyol), causing damage throughout the production cycle. Mannitol can be used to predict sucrose losses, with > 300 mg/kg %ºBrix. This work aimed to establish sugar losses and juice degradation caused by L. mesenteroides in connection with Diatraea saccharalis attacks. During the 2009 harvest season, trials were carried out in the Fronterita (Famaillá) mill fields, planted with 3 of the most important commercial varieties in the area: LCP 85-384, TUC 77-42 and RA 87-3. Ten stalk samples representing different infestation levels were analysed: unattacked cane 0% (control) and cane with 5-10%, 11-20%, 21-30%, and >31-40% of perforated internodes. Samples were measured and weighed. Three replicates of 10 stalks were analysed per variety and attack level was considered at three stages (beginning of harvest, mid-harvest, and end of harvest), while considering both cane with 5 days storage and cane without storage. Juice was extracted and mannitol was analysed, as its values can be used to predict sucrose losses when the level is higher than 300 mg/kg %ºBrix. The results showed that TUCCP 77-42 was the variety with higher sugar losses, and these increased as harvest season advanced. Storage losses were highest in TUCCP 77-42 and lowest in LCP 85-384, but on the whole harvest season losses surmounted storage losses. Deterioration measured by mannitol showed that sugarcane with 0% infestation, with and without storage, showed deterioration levels below 300 mg/kg %ºBrix. TUCCP 77-42 and RA 87-3 showed deterioration from mannitol from 5% infestation and up from the beginning of the harvest season, and LCP 85-384 only from 10% infestation at end of the harvest season.