ProMED
http://www.promedmail.org
Source: La Gaceta [in Spanish, machine trans., summ. Mod.DHA, edited]
https://www.lagacetadesalamanca.es/campo/alerta-ataque-alternaria-patata-20240813164057-nt.html
An Alternaria attack has potato producers in Salamanca on alert. This is a disease caused by the fungus _Alternaria solani_. Although it also attacks stems, on this occasion in Salamanca the attack is mainly on the leaves and the damage to the tubers is insignificant. But there is a reduction in production, and yields are lower than expected, partly due to the Alternaria attack.
The Agrarian Technological Institute of Castilla y León declares a high level in one area and places the other 2 areas it analyses at the lower "close to the treatment threshold," where symptoms are detected on the lower leaves in 10% of plants. They recommend checking plants for symptoms, paying special attention to the outer leaves. If symptoms are detected, they advise to treat them.
[Byline: Susana Magdaleno]
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Communicated by:
ProMED
[Early blight of potato and tomato is caused by the fungus _Alternaria solani_. It causes leaf spots and tuber blight on potato and leaf spots, fruit rot and stem lesions on tomato; it can also affect other solanaceous crops like capsicum. The disease can occur over a wide range of climatic conditions and can result in complete defoliation and severe yield losses. The pathogen often causes no visible symptoms until plants approach maturity.
The fungus is spread with infected plant material (including potato tubers, tomato transplants and seed), by mechanical means, wind and rain. Solanaceous weeds and volunteer crop plants may serve as pathogen reservoirs. Disease management includes use of certified clean propagation material, fungicides, crop rotation and use of cultivars with reduced susceptibility.
New strains of the fungus are emerging worldwide, some with new fungicide resistances (e.g., see ProMED posts 20161020.4574591, 20090325.1163).
Pictures
Early blight on potato:
http://www.potatogrower.com/Images/0513/EB%20lesions1_opt.jpeg,
https://www.suttonelms.org.uk/early-blight-1.jpg,
https://www.suttonelms.org.uk/early-blight-2.jpg and
https://c8.alamy.com/comp/2G112J3/potato-diseases-early-blight-isolated-on-white-2G112J3.jpg (tuber)
EB on tomato:
http://www.hort.cornell.edu/livegpath/images/early_blight_plantsx1200.jpg
Links
Information on early blight of potato and tomato:
https://www.cropscience.bayer.us/articles/cp/early-blight-potatoes,
https://vegpath.plantpath.wisc.edu/diseases/potato-early-blight/,
https://agriculture.vic.gov.au/biosecurity/plant-diseases/vegetable-diseases/target-spot-early-blight-of-potatoes,
https://www.syngenta.ca/pests/disease/en/early-blight/Potatoes,
https://extension.umn.edu/disease-management/early-blight-tomato-and-potato and
https://www.gardeningknowhow.com/edible/vegetables/potato/potato-early-blight-treatment.htm
Research on early blight fungicide resistances:
https://www.potatogrower.com/2013/05/early-blight-tranquility
_A. solani_ taxonomy:
https://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=444460
- Mod.DHA