Phomopsis longicolla Hobbs CASUAL AGENT OF SOYBEAN SEED DECAY IN CROATIA

Soybean (Glycine max (L.) Merrill), is one of the oldest and most important cultural plants in the world. On our territory, soybean was sawn in continuity until 1970, but since the end of 80-s of the last century it could be considered as a significant production (about 20 000 ha). In 2003 48 000 ha of soybean, with average grain yield 2 708 kg/ha, that almost meet domestic needs for this crop were sown in The Republic of Croatia. One of the basic problems which occurs with increasing of acreages and more intensive soybean production is a disease problem. First of all diseases were caused by phytopathogen funguses, causing about 80% of all soybean disease, and rest of 20% were caused by bacteria and viruses. In soybean breeding program at theAgricultural Institute Osijek, besides production aiming at high and stabile yielded cultivars with high grain quality, special importance is given to satisfactory resistance and tolerance of significant fungal diseases in our growing conditions. There are some diseases which almost regularly appear on soybean in our agroecological conditions. First to mention is downy mildew (Peronospora manshurica (Naum.) Syd. ex Gaum.) and diseases caused by fungus from Diaporthe/Phomopsis Complex. Phomopsis longicolla Hobbs, (teleomorf unknown). Above mentioned is different among other varieties, for its his cultural characteristic, morphology and place of infection (primary causing seed decay), and one of the most dangerous seed pathogens in main areas of soybean production in the world. Considering that fungus was discovered in our neighbouring countries there is suspicion of its presence in Croatia, danger of becoming a significant pathogen of this important industrial plant stands as a danger for our country as well.The aim of investigation was to establish presence of fungus by seed examination on several locations from a large-scale production and three year (2000–2002) studying of morphological characteristics of the pathogen, determine pathogen by culture morphological characteristics and by PCR-RFLP method, establish differences in isolate pathogenicy by artificial seed infections in the laboratory, establish differences in soybean genotype reaction on pathogen by examining seed of some soybean cultivars (promising lines) from Osijek experimental field in four years (1999-2002),set a field trial of some genotypes on Osijek location and to carry out an artificial infection with the most aggressive isolate.Fungus isolation was accomplished from soybean seed with symptoms corresponding to the one caused by Phomopsis longico