PRO/PL> Phakopsora pachyrhizi, soybean - Brazil

PHAKOPSORA PACHYRHIZI, SOYBEAN - BRAZIL
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Date: 18 Nov 2003
From: ProMED-mail<[EMAIL PROTECTED]>
Source: @gWorldwide, 18 Nov 2003 via Reuters [edited]


Brazilian growers arm to fight Asian soy rust
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Soybean producers across Brazil have armed themselves this season in a 
battle against possibly the biggest threat to their livelihood -- a 
virulent strain of Asian soy rust caused by _Phakopsora pachyrhizi_.

"The whole state is worried," said head agronomist Andre Neves Santos at 
the Moises Sachetti farms in Brazil's No. 1 soy state, Mato Grosso. "I've 
been to 5 training seminars on how to identify and combat rust fungus in 
the last few months."

According to the U.S. Department of Agriculture, Brazil will become the 
world's No. 1 exporter of soy in 2003, displacing the USA.  Experts agree 
that Brazil's future leadership in soy production will depend on how well 
it contains Asian rust, the most destructive soybean leaf disease, which 
reduces yields by up to 80 percent.

Rust first showed up in Paraguay in 2001 and has since spread through 
Paraguay, Brazil, Bolivia, and parts of Argentina. U.S. producers are 
terrified at the possibility of the fungus reaching U.S. soy fields.

Of the main soy states affected last season, Mato Grosso suffered the most 
because growers were caught off-guard, unconvinced it could travel so fast 
across Brazil's massive 20-million-hectare soy belt.

"95 percent of producers in the state have already purchased all the 
fungicide they expect to need this season," said Cristina Santos, who added 
the cost of fungicide and its application would be expensive. Cost 
estimates of soy experts are around $50 per hectare.

Rust showed up late in the growing cycle last season, reducing yield by 3 
million tonnes off the 2002/03 crop, lowering Brazil's output to 52 million 
tonnes, said Jose Tadashi Yorinori, Brazil's top soy rust expert at the 
national plant research agency (Embrapa).

As Brazil enters the peak of a new Sept-Dec planting season, Mato Grosso 
has already registered its first outbreaks of rust. "It began earlier this 
year," said Yorinori. He said losses were pronounced in Mato Grosso and 
Bahia last season because producers didn't identify the rust and spray soon 
enough. But this is also a particularly virulent strain of rust.

Yorinori said tropical varieties of commercial soy seed that were 
previously thought to have some rust resistance last season did not have 
resistance to this virulent strain. Producers will have to rely largely on 
fungicide until new rust-resistant strains are developed -- but that is 
likely to take years.

Embrapa has identified one soy variety (BR-134) that is resistant to rust, 
but it is not adapted to many growing regions in Brazil. Embrapa is working 
with private sector firms to find and develop more resistant soy varieties.

For now, producers are betting on a tough spraying campaign to hold off the 
disease.

[Byline:Reese Ewing]

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ProMED-mail
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[Soybean rust appeared in South America in 2001 and now occurs in 
Argentina, Brazil, and Paraguay. As of November 2002, USDA scientists had 
screened 1000 of 4000 public and commercial soybean lines against a mixed 
Pr population of 4 isolates from Zimbabwe, Thailand, Brazil, and Paraguay. 
Most were susceptible, but a few show a resistant reaction type or reduced 
numbers of lesions on infected leaves. Fungicides appear to be the only 
workable disease management strategy at present. Several efficacy trials 
are underway in Africa and South Africa to select candidate fungicides for 
rust control. Only 2 effective fungicides are currently registered for use 
in soybeans. In trials conducted outside the USA, 4 additional products 
have been identified as effective against Pr, but are not currently 
registered for use in soybeans. - Mod.DH]

[see also:
Soybean rust - Brazil 20030426.1022
Soybean rust - Zimbabwe (Arcturus) 20030222.0456
Soybean rust - Brazil (Sao Paulo State) 20030124.0214
Phakopsora sp., soybean, yield loss - Uganda 20030119.0176
Soybean rust - Brazil (Mato Grosso & Bahia) 20030415.0917
2002
----
Phakopsora sp., soybean rust - S. Africa, Argentina 20021231.6167
Phakopsora sp., soybean rust - South Africa 20020206.3495
Phakopsora sp., rust, soybean - Zimbabwe 20020110.3220
2001
----
Phakopsora sp., soybean rust - South Africa (03) 20011213.3014
Phakopsora sp., soybean rust - South Africa (02) 20010405.0679
Phakopsora sp., soybean rust - S. Africa (confirmed) 20010322.0569
Phakopsora sp., soybean rust - South Africa 20010312.0505
Phakopsora sp., soybean rust - Africa (02) 20010310.0491
Phakopsora sp., soybean rust - Nigeria 20010309.0486
Phakopsora sp., soybean rust - Africa 20010309.0487]
......................................dh/pg/dk

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