Two field trials were conducted during the successive seasons 1999/2000 and 2000/2001 to study the effect of solarization, farm yard manure (FYM), two bio-control agents (Trichoderma harzianum and Bacillus subtilis), two agricultural chemicals (Ca(OH)2 and sulfur) and two fungicides (Vitavax captan and Rizolex T) for the control of Sclerotinia sclerotiorum on Centaurea spp. (blue bottle and sweet sultan) plants. Hence, histological studies showed that, Trichoderma harzianum parasitized sclerotia of Sclerotinia sclerotiorum and absolutely destroyed and converted to spores of T. harzianum within 12 days under laboratory conditions.
Results show that, Centaurea moschata (sweet sultan ) was more susceptible to the rot disease incidence than Centaurea cyanus (blue bottle). Also, the disease incidence increased by increasing the period 2 to 3 and 4 months. On the other hand, Vitavax, (Ca(OH)2, Trichoderma harzianum and farm yard manure (FYM) were the most effective for the disease control and reduction the length of disease part as well as number and weight of sclerotia in blue bottle plant during the two tested seasons. While, bio-control agents (T. harzianum and B. subtilis), FYM and fungicides were most effective on the sweet sultans. Vitavax, bio-control agents and Ca(OH)2 were effective for reduction the yield of sclerotia (number and weight/plant) in blue bottle. Meanwhile, T. harzianum and Vitavax as well as Ca(OH)2 were only the effective in sweet sultan during the two seasons.
Concerning the vegetative growth characters ( plant height, number of leaves / plant, fresh and dry weight of leaves/ plant, number of branch / plant, fresh and dray weight of stem / plant), root growth characters ( roots size / plant, length of roots / plant, fresh and dry weight of root / plant) and flowering characters (number of days to start flowering, diameter of flower, number of flower / plant, fresh and dry weight of flower / plant, number of attached leaves on peduncle, diameter of peduncle, length of peduncle , fresh and dry weight of peduncle / plant ), bio-control agents, agricultural chemicals and Vitavax were more effective than other integrated control treatments for improving in all studied vegetative growth, roots and flowering parameters in blue bottle during the two tested seasons. While, bio-control agents and FYM, solarization and Vitavax only were effective in sweet sultan.
In addition results also indicated that, bio-control agents and sulfur were significantly increased in chlorophyll a, b and carotenoids. The same was obtained for total carbohydrates and total phenols (free and conjugated) in the blue bottle. While, T. harzianum, FYM and solarization were effective on sweet sultans during the two seasons.
Key words: Agricultural, biological, Sclerotinia, Trichoderma, Bacillus, sulfur, lime, fungicides, productivity Centaurea
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