Always a major threat to the world’s rice crop, blast is being studied by a large contingent of scientists keen to defeat — or at least stay ahead of — the fungal disease.

In mid-August, several hundred of those scientists will arrive in Little Rock for a conference on blast. While in the Mid-South they will hear the latest on research, trade information and tour Arkansas rice fields.

Rick Cartwright, a University of Arkansas Division of Agriculture plant pathologist, spoke with Delta Farm Press about blast and the conference. Among his comments:

On the situation with the blast in the Mid-South and the world…

“Blast disease is one of the top yield-constraint problems in the world’s rice production. Wherever you’re growing rice, blast will be one of the important disease risks for the crop.

“So, we spend an awful lot of money and time trying to prevent blast epidemics. If you don’t prevent them, situations like the one in Arkansas last year can happen — some growers saw near total yield loss. And I’m not talking about patches here and there, but across entire fields. We noted yields as low as 30 to 40 bushels per acre in some cases.

“The disease can be relatively easy to manage. But it is very weather-dependent. When you have rainy, late-planted years like 2009, and if you’ve done the wrong thing — say, planted a susceptible variety in the wrong field — the disease can be uncontrollable.

“It’s a very dramatic disease, very unpredictable. When I say researchers spend lots of time and effort studying it, it’s mainly to prevent what could happen under the right environmental conditions.

“Sheath blight is an interesting disease to contrast with blast. Each year, we largely know what sheath blight will do. It’s a percentage game — it’s going to take a percentage of your crop but we know how to predict it. And that percentage varies a bit with the weather but not nearly as dramatically as blast disease.

“So, blast scares everyone. If you don’t control sheath blight, you might cut 5 to 30 bushels less. If you don’t control blast, you could be out of business.”

On why research on blast is so challenging…

“The blast fungus itself has what I like to say is its own ‘research program.’ It has a lot of labor: millions and millions of baby blast fungi because it’s so productive when it reproduces. And its ‘research program’ is based on genetics. It’s out there in the environment changing all the time.

“Meanwhile, we’re changing rice crop management to try and keep up with the fungus.

“The disease, because it has so many ‘children,’ quickly adapts to our efforts at management. After all, we’re messing with its basic right to survival. What we do is put a lot selection pressure on the fungus. It responds with its breeding program and produces races, or strains, that can overcome things like resistance genes we try to use in rice. Long-term it can also overcome fungicides and other practices we throw at it.

“It’s almost like a long-term war. That’s why we must spend so much long-term research on this pathogen.”

On how research on blast has become a ‘model system’…

“So much labor has gone into controlling this disease around the world, that the efforts have become a sort of model system for studying interactions between a fungal plant pathogen and a host plant. So, the research that’s being done not only has the benefit of managing blast in rice, but a lot of the principles discovered in that work have been — or potentially can be — used in other crops and settings. There’s just a bunch of fundamental research going on blast.”

On the international blast conference to be held in Little Rock…

“Because there are so many scientists around the world working on this model system and important disease, it’s critical to get together once in a while. At that meeting, they’re able to share new ideas and data. That’s the purpose of the International Rice Blast Conference.

“This is the fifth such conference where some of the most important scientists working on rice diseases get together. The (conferences) aren’t held annually and the last was in China.

“This conference (Aug. 12-14) is being hosted primarily by Yulin Jia and Anna McClung (of the USDA-ARS Dale Bumpers National Rice Research Center near Stuttgart, Ark.) and James Correll and Fleet Lee (of the University of Arkansas Division of Agriculture’s Depart of Plant Pathology and Rice Research and Extension Center).”

On a conference tour…

“Usually these types of conferences are kind of dry. But this time, the whole group — 200 or so — will tour our facilities and the Grand Prairie rice region to see how we grow rice in the South and observe blast in the field.

“That should allow the scientists from other countries a better perspective of our advanced rice production systems here, as well as some of the annual challenges our growers face.”

e-mail: dbennett@farmpress.com