Rice panicle blight caused by Burkholderia glumae is a new challenge for Latin American rice growers. The disease causes sterile panicles, reducing yields by up to 80% in some regions. The pathogen was first reported in Latin America in 1989 but has become a more significant problem recently due to environmental conditions and susceptible cultivars. The research group used Koch's postulates to confirm B. glumae as the causal agent. They developed a scale to evaluate disease tolerance in seedlings as a first step to identifying more tolerant varieties. Screening Latin American cultivars identified variation in responses that could be used in breeding programs to develop more resistant varieties and manage the disease threat.

1. Rice Panicle Blight, A New challenge for Latin America Rice Growers
Prado, G., Aricapa, M.G., Fory, P., Pérez, C.R., Saavedra, E., Correa, F., Mosquera, G.M.
Rice Pathology-CIAT. Kilometro 17 Recta Cali-Palmira
Introduction
Rice panicle blight caused by Burkholderia glumae is the
blight, glumae,
new challenge that farmers are facing in Latin America
countries nowadays while has been reported in Japan,
Taiwan, Korea, and United States several years ago. Disease
symptoms appear mainly in flowering stage producing sterile
panicles (Figure 1a and 1B) even although brown spots on
sheaths and flag leaf are also seen. It was reported in Latin
America in 1989 (Zeigler and Alvarez), but is just until 2004
that become an important disease because of its impact on Figurae2A. Leaf symptoms of B. glumae reproduced in greenhouse. Figure
2B, panicle symptoms of B. glumae reproduced in greenhouse.
rice production. Yield losses have been reported to be up to
80% in Panama and Colombian Caribbean region, what has
been associated with id l environmental conditions and
b i t d ith ideal i t l diti d
susceptible cultivars present in these regions that favor Disease response ranges allowed designing an evaluation
disease development. In several cases, B. glumae infection scale that could help in the identification of tolerance sources in
has been associated with a Mite-Fungus-Bacteria complex seedling stage. Thus, level 1 to 3 corresponds to tolerance,
Camargo et al, 2006). First disease out brakes in Central level 5 is intermediate, and level 7 to 9 means susceptible
America were associated jointly to spinki mite mite, (Figure 3)
3).
Steneotarsonemus spinki and Sarocladium oryzae fungus.
CIAT has focused its research to study the bacteria as causal
agent to try to rule out its contribution inside the complex.
Figure 3. Evaluation scale establish for panicle blight screening.
Figure1A. B. glumae symptoms on sheaths and flag leaf. Figure 1B, B. glumae infecting Conclusions
panicle directly.
• Obtained results support the association of B. glumae as
Materials and Methods causal agent of rice panicle blight in the Caribbean coast of
Colombia. Bacterial id ifi i was confirmed b
C l bi B i l identification fi d by
• Infected rice seeds collected from Colombian Caribbean molecular diagnostic tools.
coast region were processed following Koch postulates • Development of an evaluation scale will allow CIAT and local
procedure. germplasm characterization that later could be used in
Latin America region.
• A Rice cultivar set showing different degrees of disease
g g • This study coupled to additional information supplied by
progression (tolerant, intermediate, and susceptible) was FEDEARROZ is being used to strength disease
used to develop an evaluation scale. management programs; however research in this matter
• Latin America rice cultivars (318) were used for screening needs to continue.
on their response to the disease.
REFERENCES
Results and Discussion –Camargo, I., Quirós, E., Von Chong, K., Zachrisson, B.,
González, F. 2006. Manejo del complejo BAH. IDIAP.
Panamá.
Use of Koch postulates procedure allowed disease
–Correa, F., Pérez, C.R., Saavedra, E. Añublo bacterial de
associated-symptoms reproduction on seedlings and panicles
la panicula del arroz. 2007. ARROZ. 57:468
under greenhouse conditions (Figure 2A and 2B). Moreover,
–Zeigler, R.S., Alvarez, E. 1989. Pant Disease 73:368.
seed sterility could be associated to B. glumae directly.
:
Funding
FONTAGRO Project No. FTG-311/2005
No FTG 311/2005