Assessment of Three Artificial Inoculation Methods for Sugarcane Smut Disease Incited by the Fungus Ustilago scitaminea (Syd.)

Abstract

A field experiment was conducted during 2000/01, 2001/02
and 2002/03 seasons, at the Sugarcane Research Centre, Geneid, Sudan.
The objectives of the study were (a) to assess the efficiency and ease of
use of three artificial smut inoculation methods; namely, Taiwanese pin-
prick (TPPM), dip (DM) and natural spreader-row infection (NSIM) and
(b) to evaluate the field response of the tested genotypes to smut. Nine
sugarcane genotypes were tested against three checks, in a randomized
complete block design with three replications. The mean percentage of
smut infection was 2.81, 1.96 and 2.26 for TPPM, DM and NSIM in plant
cane (PC); 5.51, 4.39 and 7.4 for the first ratoon (R1) and 6.54, 6.06, 8.66
for the second ratoon crop (R2), respectively. TPPM and NSIM gave
slightly high mean percentage of infection values in PC and R1. However,
these values were almost similar in R2 for all three artificial inoculation
methods tested, indicating the general effectiveness of the three methods
in inciting the disease. Therefore, they can all be used; the choice of any
one of them should be according to local circumstances and objectives of
the study. However, considering the time saved and ease of use, DM is
preferred. Four sugarcane genotypes BJ 82105, B 70531, COC 671 and
TUC 75-3 had reaction types similar to the resistant checks CO 997 and
CO 6806. Three sugarcane genotypes BT 74209, DB 75159 and B 79136
rated either resistant or highly resistant; thus, they are equally suitable for
inclusion in the production system. Two sugarcane genotypes, BJ 7938
and BJ 7451, however, had a moderately susceptible reaction type similar
to the susceptible check CO 527 and are, therefore, not suitable for
commercial production.