AgroPages-Few fungicides to control the most aggressive disease in soybean, the largest fungicide market in Brazil-Agricultural news

Flavio Hirata

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According to Dr. Tadashi Yorinori, PhD, senior agronomist researcher, soybean diseases in Brazil, the annual yield losses are estimated at US$ 1 billion before the rust (Phakopsora pachyrhizi) epidemics in 2002. Currently, the annual soybean losses due to this disease are estimated at US$ 1.5 billion. Estimated total loss from 2001/02 to 2014/15 is more than US$25 billion. In Paraguay where 3 million hectares of soybeans were planted in 2014/15, the yield losses caused by rust were estimated at US$ 860 million.

In 2004/05 there was the first case of efficacy loss of the fungicide flutriafol; in 2007/08 the same happened with tebuconazole. Since then most triazoles and the mixtures with strobilurins have progressively lost efficacy. Currently there are only four formulated products of active ingredients that present efficacy higher than 60% when compared with the unsprayed check plots on which disease severity reached 76.9% defoliation. This situation renders the soybean production in Latin America highly vulnerable, not only to future soybean rust epidemics but also to other diseases and pests.

Tropical and subtropical weather in Latin America are blessed by the fact it is possible to harvest food and agricultural commodities for the humankind during 12 months of the year. Nevertheless, as it happens when all seems too good on one side, there is always the other side of the coin. The blessing of Nature demands a counterpart, which is the understanding of how the tropical and subtropical environment reacts to the aggression imposed by the agricultural activities.

Agriculture is a biological activity where Nature works in a most dynamic and versatile form, with actions and reactions that are often unexpected. The understanding of the Nature´s modus operandi must come from exhaustive research on the biological agents involved, on how to manage them in order to avoid their noxious effects. In turn, the results of investigation, knowledge and the technologies accrued should be transferred fast, efficient and clearly to the end-users, the farmers. In turn, the latter must be properly instructed and trained on how to implement these new technologies in order they would be useful, safe and durable.

Soybeans in the four largest producing countries in Latin America (Brazil, Argentina, Bolivia and Paraguay) have an extraordinary expansion in acreage and yield in the last 10 years. Brazil is currently growing 35 million hectares. Nevertheless, in a similar trend of the expansion in acreage there was an evolution of the pest problems. Besides species diversity, genetic variability of the pests (insects, pathogens and weeds) are expressed at each crop season as new fungal, insects and weed populations that are more tolerant or resistant to the chemical control routinely used.

In the case of insect pests, for example, many species of caterpillars that were hosted specifically on annual crops such as corn, soybean and cotton became polyphagous and are damaging any crop present in the field. Besides becoming more tolerant to the effects of regular chemical pesticides, the year-round presence of host plants favors the multiplication of those insects that do not need to overwinter. This situation favors a rapid evolution of pesticide tolerant individuals existing within the original insect population, explains Dr. Yorinori.

Besides the difficulties encountered by the chemical industries in the developing new effective, safe and durable molecules, which may take several years, the high cost may make soybean production unfeasible for many farmers.

Thus the challenging question facing the future of agriculture in the tropical and subtropical environment is “will it be possible to restore the current molecules in use through new formulations/combinations of mixtures, dosages and new more efficient adjuvants?”

The facts above indicate that it is of utmost importance to urgent call for a collective participation of all segments involved in the pesticide chain, including manufacturers, distributors, research institutions, regulatory agencies, farmers in training on proper use of the pesticides for a better crop management, finalizes Dr. Yorinori.

Having Brazil is the biggest pesticide market in the world, AllierBrasil is promoting the 8th Forum AllierBrasil and this is one of the subjects that will be deeply discussed in Qingdao, next January 7th and 8th, said Mr. Flavio Hirata, MBA, consultant to AllierBrasil.