A ProMED-mail post
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Date: 18 Mar 2010
In Rostov region sunflower seeds infected with phomopsis
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The upcoming spring sowing caused an increase of sunflower seed trade in the Rostov region. Rosselkhoznadzor [Russian Federal Service for Veterinary and Phytosanitary Surveillance] strongly recommends to check for the availability of quarantine documents before seed purchase. In 9 districts of Rostov region seeds infected with phomopsis were found, and state inspectors have seized 500 tons of infected seed out of 3000 tons screened.
Sowing of these 500 tons of seeds would have resulted in losses equivalent to crops of about 100 medium-sized farms. The head of the quarantine laboratory commented that the situation has improved this year because of established screening practices. Rosselkhoznadzor experts suggest that the wet weather was the cause of the spread of infection.
The infected seeds are being treated with chemicals and checked once more before sowing. Sometimes a 2nd treatment is necessary after which most of seeds are suitable for sowing. There is no 3rd treatment attempt because seeds would not be viable any more. Farmers have 2 options to process seeds not fit for sowing for oil
extraction: for edible oil, or for oil for technical uses. For the 1st option, the value of the seeds is one 10th of the original price, and even less for the 2nd option.
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[Brown stem canker (also called phomopsis, grey stem spot) of sunflower is caused by the fungus _Diaporthe helianthi_ (previously _Phomopsis helianthi_). It is a serious disease of the crop in many temperate regions with yield losses of around 50 percent reported, for example from some Russian areas. Symptoms include necrotic leaf lesions extending towards the petiole leading to leaf necrosis, followed by stem cankers which may girdle the stem and result in collapse of the plant.
The disease is favoured by warm, humid conditions. The fungus overwinters on plant debris left in the field and can be spread with plant material including seed, by mechanical means and human activities. Disease management includes phytosanitation to remove inoculum (such as deep plowing of crop residues), cultural methods (crop rotation, wide row spacing), fungicide treatments of crops and seed and use of resistant sunflower varieties and hybrids.
In Russia, the disease was reported 1st in 1990 and is spreading.
Moldova, Ukraine and the Northern Caucasus are reported to be currently the most seriously affected areas in the region.
Related _Diaporthe_ species and strains (for example _D.
phaseolorum_) are known to be associated with stem cankers and some other diseases of soybean where they can cause high losses.
Maps
Russia:
Russian regions:
Pictures of _D. helianthi_ symptoms:
(whole plant)
Links
Information on brown stem canker:
_D. helianthi_ taxonomy:
Rosselkhoznadzor:
- Mod.DHA]
[see also:
2009
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Fungal diseases, soybean - USA 20090817.2912
2007
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Top dieback, soybean - USA (IA) 20070827.2814
2006
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Northern stem canker, soybean - USA (ND): 1st report 20060427.1222
2004
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Diaporthe spp., stem canker, soybean - USA (WI) 20040519.1340
2002
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Diaporthe spp. soybean stem canker - Argentina 20021201.5944 Sudden death syndrome, soybean - USA (DE & MD) 20020710.4721
2001
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Diaporthe spp., soybean stem canker - Argentina 20010227.0387
1999
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Plant pests - Russia 19991202.2114]
Topics
Species
