The Hindu Business Line : Scientists deny Pak claims on `infested' wheat

SCIENTISTS at the Indian Council of Agricultural Research (ICAR) have refuted Pakistan's claim about Indian wheat being infested by Karnal Bunt (KB) disease.

"There has been no outbreak of KB in our wheat during the last five years. The last time we had any significant incidence was in the 1995-96 crop year," said Dr A.K. Sharma, Principal Investigator (Crop Protection) at ICAR's Directorate of Wheat Research (DWR) in Karnal.

The Pakistan Government had on Sunday announced that it would not extend transit facility for Indian wheat being supplied to Afghanistan under the World Food Programme on the ground of it being infested by KB, a disease caused by a fungal pathogen known as Neovossia indica. The disease is basically seed-borne, which is transmitted to the soil upon planting. The fungal spores, then, germinate in the `sick' soil and reach the earhead of the growing wheat crop, thereby infesting the grain.

Dr Sharma said that the wheat grown could be infested with KB only under very specific climatic and environmental conditions. "The disease-prone stage for the crop is mainly at the time of earhead emergence, which is usually during the first and second week of February (i.e., about two months prior to harvest and two-and-a-half months after sowing). If there is frequent rainfall, high relative humidity and low temperatures in the evenings during this vulnerable stage, there is a possibility that the spores would reach the earhead," he noted.

However, during the last five years, there have been no such adverse climatic conditions. The Ludhiana-based Punjab Agricultural University (PAU) has been carrying out extensive surveys of wheat samples collected from different grain mandis of Punjab, which is considered to be the State most prone to the pathogen.

According to Dr G.S. Nanda of PAU's Wheat Section, the frequency of KB-infected samples amounted to as high as 70.3 per cent during 1996, which had steadily come down to 27.3 per cent, 35.7 per cent 45.8 per cent and 15.1 per cent in the following years. In the 2001 season, as much as 92.1 per cent of the wheat samples were found to be KB-free.

But more than the incidence of KB per se, what really mattered was the intensity of the infection. Around 99 per cent of the samples in 2001 had infection levels of 0-0.25 per cent, which was well within the prescribed limits for seed certification and quarantine specifications for exports. The proportion of samples falling within the safe 0-0.25 per cent infection limit stood at only 63.2 per cent in 1996, which had since then risen to 94.7 per cent in 1997, 94.4 per cent in 1998 and 87.2 per cent in 1999. The average infection levels in the samples, too, had come down from 0.64 per cent in 1996 to an insignificant 0.004 per cent now, Dr Nanda said.

Apart from climatic factors, Dr Sharma said that the introduction of new disease-tolerant wheat varieties were also responsible for the downward trend in the incidence of KB. "Till the mid-nineties, the varieties grown in north-west India were dominated by HD-2009 (Arjun), HD-2285 and HD-2329, which were specially vulnerable to Karnal Bunt. But now, we have replaced these with new varieties such as PBW-343, which alone occupy around 4.5 million hectares or nearly 70 per cent of the wheat area in the region," he added.

In addition, in the last 3-4 years, farmers have also been sowing wheat relatively early, which meant that the spores germinated prematurely and did not have the required potential to cause the disease by the time the host plant reached the vulnerable earhead emergence stage.

As regards the general perception about Indian wheat being particularly infested with KB, Dr Sharma said that this stemmed more from the trade mistaking `Black Point' for the former. "Black Point is caused by Alternaria alternata, which is a much weaker fungal pathogen having no quality or quarantine significance. Just as Karnal Bunt, this pathogen too causes blackening of the grain, though without leading to any loss of quality or risk of infection. In fact, it is not even listed as a quarantine pest anywhere," he pointed out.

Send this article to Friends by E-Mail

Stories in this Section
BSES places hurdles in DPC bidding process

Tata Tea Q3 net up at Rs 20.67 cr

Satyam Computer posts 36 pc rise in Q3 net

Scientists deny Pak claims on `infested' wheat

Cadila to launch Fosinopril

DCA relaxes norms for differential voting rights

SEBI panel moots early IPOs by MNCs, banks