EFFECTS OF SAGE LEAFHOPPER FEEDING DAMAGE ON HERBAGE COLOUR, ESSENTIAL OIL CONTENT AND COMPOSITIONS OF TURKISH AND GREEK OREGANO

Turkish (Origanum onites L.) and Greek oregano (Origanum vulgare L., ssp. hirtum (Link.) Ietswaart) species were investigated to determine herbage colour, essential oil content and composition changes due to sage leafhopper (Eupteryx melissae) (Hemiptera: Cicadellidae) infestation. Sage leafhopper population on both Turkish and Greek oregano did not significantly vary. The sage leafhopper damage was more severe in the lower part of the canopy than the middle and upper parts. Extensive sage leafhopper feeding dramatically reduced essential oil contents, resulting in 28.8 and 34.8% reductions for Greek and Turkish oregano, respectively. Carvacrol, the major essential oil component of both oregano species, did not remarkably vary between leafhopper infested and non-infested plants. With respect to herbage colour, the brightness, redness and yellowness values were significantly different between infested and non-infested plants. Sage leafhopper damage increased brightness and yellowness but decreased greenness of the oregano herbage. To avoid the feeding damage, it is essential to detect the sage leafhopper problem as early as possible and certain control practices are necessary when the infestation is high.Turkish&nbsp;(Origanum onites L.) and&nbsp;Greek&nbsp;oregano&nbsp;(Origanum vulgare L., ssp. hirtum (Link.) Ietswaart) species were investigated to determine&nbsp;herbagecolour,&nbsp;essential&nbsp;oil&nbsp;content&nbsp;and composition changes due to&nbsp;sage&nbsp;leafhopper&nbsp;(Eupteryx melissae) (Hemiptera: Cicadellidae) infestation.&nbsp;Sage&nbsp;leafhopperpopulation&nbsp;on&nbsp;both&nbsp;Turkish&nbsp;and&nbsp;Greek&nbsp;oregano&nbsp;did not significantly vary. The&nbsp;sage&nbsp;leafhopper&nbsp;damage&nbsp;was more severe in the lower part&nbsp;of&nbsp;the canopy than the middle and upper parts. Extensive&nbsp;sage&nbsp;leafhopper&nbsp;feeding&nbsp;dramatically reduced&nbsp;essential&nbsp;oil&nbsp;contents, resulting in 28.8 and 34.8% reductions for&nbsp;Greek&nbsp;and&nbsp;Turkish&nbsp;oregano, respectively. Carvacrol, the major&nbsp;essential&nbsp;oil&nbsp;component&nbsp;of&nbsp;both&nbsp;oregano&nbsp;species, did not remarkably vary betweenleafhopper&nbsp;infested and non-infested plants. With respect to&nbsp;herbage&nbsp;colour, the brightness, redness and yellowness values were significantly different between infested and non-infested plants.&nbsp;Sage&nbsp;leafhopper&nbsp;damage&nbsp;increased brightness and yellowness but decreased greenness&nbsp;of&nbsp;the&nbsp;oreganoherbage. To avoid the&nbsp;feeding&nbsp;damage, it is&nbsp;essential&nbsp;to detect the&nbsp;sage&nbsp;leafhopper&nbsp;problem as early as possible and certain control practices are necessary when the infestation is high.</p

Studies on different herbicide application methods in second-crop maize fields

Overall application of herbicides with hollow cone nozzles is common practice in second-crop maize in the Cukurova Region of Turkey. Effective integrated weed management tactics are needed for this region. Acetochlor and nicosulfuron, two commonly used herbicides in maize production, were applied pre-emergence and post-emergence, respectively. Spinning disc nozzles with a reduced spray volume did not improve weed control and with a reduced herbicide dose gave inadequate weed control. Banding was as effective as broadcast application. Different bandwidths with even flat fan nozzles, 15, 20, 25, 30, and 35cm, gave similar weed control and maize yield. Banding decreased herbicide and water use by up to 78%. © 2004 Elsevier Ltd. All rights reserved.Ministry of Agriculture and Rural DevelopmentAuthors thank to Dr. Martha Rowe because of her proof reading of the manuscript. The study was supported by the Ministry of Agriculture and Rural Affairs, Turkey under the Project No. TAGEM/BS/96/01/05/203