The Cenicaña Disease Diagnosis Service warns about the increase in leaf scald diseases, soca rickets and yellow leaf in propagating varieties.
To ensure the quality of the seed produced and sown by the Colombian sugarcane agribusiness, Cenicaña offers the Disease Diagnosis Service, which analyzes leaf tissue samples of plants from commercial lots and seedbeds sent by sugar mills and suppliers .
As a result of the timely diagnosis, the strategy of planting healthy seedlings and the comprehensive management of diseases carried out by the sector in the Cauca river valley, over the years it has been possible to reduce the prevalence and incidence of diseases such as leaf scald (LSD), soca rickets (RSD), cane mosaic (SCMV) and yellow leaf (SCYLV), keeping them below economic damage levels.
However, an analysis of the results of the diagnosis during the first semester of 2015 in comparison with 2014 and previous years indicated that some of the new varieties such as CC 97-7170, CC 01-1940 and CC 01-746, among others, register high average incidences for soca rickets and leaf scald with respect to CC 85-92 in specific situations; for example, 16.7% average incidence in samples positive for RSD in CC 01-1940, quite high value. Seed lots have been diagnosed with incidence of RSD up to 75% and LSD up to 30% of affected plants in the sample.
With regard to the yellow leaf, an accelerated increase in the prevalence of the disease throughout the region in recent years, mainly in the central and southern areas. According to the Service, the prevalence went from 4.3% in 2011 to 22.7% in 2014, and by October 2015 it is already in 39.3% of samples positive for the virus, in which batches with maximum values have been registered between 70% and 100% of affected plants.
According to the evidence, all varieties can be infected in different percentages; However, as of October 2015, the most prevalent ones were SP 71-6949 (77.6%), RB 73-2223 (73.6%), CC 91-1606 (50%), CC 93-4181 (44.7%) and CC 01 -1940 (52.4%). The latter was the most analyzed and the most sown as of October 2015, with 1020 of the 2048 samples evaluated.
The high pressure in the sowing of these varieties is probably leading to the use of seed without the proper diagnosis and health control, which translates into the increase of SCYLV and the resurgence of systemic diseases of bacterial origin transmitted through infested seed and tools. , which can reduce production. Hence the importance of not lowering our guard in the processes and recommendations for the establishment and proper management of seedbeds.
Prevalence: proportion of sick samples with respect to the total analyzed in a given time.
Incidence: quantification of infection. Number of positive leaves in each sample consisting of twenty leaves.