[Some important insect pests of kohlrabi and their possible role in dissemination of soft rot bacterium in Iraq]
1990
Al-Janabi, G.D. | Al-Azawi, A.F. | Tamimi, K.M.
Kohlrabi, Brassica oleraceae var. caularapa (Cruciferae) is extensively planted in the central provinces in Iraq. Lately the crop became subject to great losses resulting from severe attacks of certain insect pests, as well as a soft rot bacterial disease, which led farmers to shift to other crops. This study aimed towards the identification of the existing insect and disease pests, their relative importance, and relationships, in an endeavor to lay down appropriate recommendations for their control. Survey revealed three insect pests, namely Hellula undalis (Lep., Pyralidae) whose larvae bore into the heads, the weevil Baris opiparis (Col., Curculionidae), which also bore into the heads, and the shoot fly Atherigona orientalis (Dip., Muscidae) that accompanied H. undalis infestations. A disease agent identified as soft rot bacterium, Erwinia carotovora ssp. carotovora caused head rot and emitted a foul oder. Field observations revealed that H. undalis and B. opiparis appeared by mid-May while A. orientalis and E. c. spp. carotovora infestations occurred from mid-July. Peak populations of H. undalis appeared in July, B. opiparis in August, and A. orientalis and the rot disease about mid-September. Infestation by all pests disappeared by the end of the growing season. A highly significant positive correlation between A. orientalis population and the rot disease incidence took place. A hypothesis is proposed on the mode of transmission of the bacterial disease among kohlrabi plants
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