Abada K. A.,
Faten M. Abd-El-Latif,
Hala A.M. El-Dakar
Pages: 39-46 Published Online: Feb. 1, 2015
The aim of science in the twenty first century, arguably, is to enhance the depend on safe methods of disease management rather than pesticides in order to obtain safe plant products.
Egyptian clover is the most perennial forage crop grown in Egypt and diseases are the most important constrains. Clover rot is the important disease all over the world including Egypt. The disease infects the crown and roots causing crown and stem-rot and the new growth wilts, dies, and may be covered with fungus growth. Hard, black, fungus bodies (sclerotia) are produced in diseased tissue. The disease, generally, appears in the beginning of December and become severe during January and February in northern governorates. The infection originates from the ascospores realed from the apothecia. The heavily infected leaves become grayish brown, wither and become over run with white mycelium which spreads to the crown and roots. Later on crown and basal parts of young stem show brown soft rot, which extends downward to the root. Field observations reveal that in dry areas and years, the disease is out of sight and mind.
The fungus has a wide host range, including many species in the composite and crucifer families, which makes control more difficult.
Culture filtrate of Bacillus and Trichoderma isolates resulted in different degrees of reduction to the growth of S.sclerotiorum and the fungus failed to grow on the concentration of 75 and 100 %, respectively.
All the tested bioagents resulted in significant reduction to the germinated sclerotia of S.sclerotiorum and the tested Trichoderma isolates were more efficient (more three times) in reducing the viability of sclerotia than Bacillus isolates.
The tested bioagents, i.e. B.thuringiensis-1 and T.harzianum-3 as well as soil solarization resulted in significant reduction to the severity of clover crown and stem-rot with significant increase to the green forage yield compared with control treatment. In addition, T.harzianum-3 was more efficient than B.thuringiensis-1 and solarization, when each of them was applied alone. However, the combination between solarization and any of the tested bioagents was more efficient in reducing both crown and stem-rot severity and increasing the green forage yield than when each of them was used alone. Moreover, the combination among B.thuringiensis-1 + T.harzianum-3 + solarization was the most efficient in this regard, which no apparent infection by crown and stem-rot were observed and the highest green forage yield was obtained.