Evaluating the effects of application modes and soil types on the herbicide efficacy and crop yield of pendimethalin and clomazone on transplanted pepper (Capsicum annuum L.)

G. Glatkova¹* and Z. Pacanoski²

¹University Ss. Cyril and Methodius, Agriculture Institute, 16-ta Makedonska brigada 3A, MK1000 Skopje, Republic Macedonia
²University Ss. Cyril and Methodius, Faculty for Agricultural Sciences and Food, 16-ta Makedonska brigada 3, MK1000 Skopje, Republic of Macedonia
*Correspondence: gordana_glatkova@yahoo.com

Abstract:

Field experiment was carried out in 2014 and 2015 in two locations Kochani and Drachevo in Republic of Macedonia to evaluate the efficacy and crop safety of pendimethalin and clomazone on transplanted pepper according to mode of application, (pretransplant -PRE-T and pretransplant incorporated -PTI) and soil types (alluvial soil and vertisol). The weed population in both years and locations mainly consisted annual spring and summer grasses and broadleaf weeds. Weed competition significantly reduced pepper yield. There was no recorded difference between the efficacy of pendimethalin PRE-T and pendimethalin PTI. However, the efficacy of clomazone PTI was higher than that of clomazone PRE-T in both experimental years and locations, indicating incorporation into soil if critical for clamazone. Both pendimethalin and clomazone had low efficacy on Solanum nigrum L. Pepper plants were not visibly injured by any herbicides treatments. In summary, locations and soil types did not affect herbicide efficacy and pepper selectivity. Pepper yield was markedly affected by herbicide efficacy in both years and locations.

Key words:

Over-wintering of the Colorado potato beetle (Leptinotarsa decemlineata Say) in field conditions and factors affecting its population density in Estonia

K. Hiiesaar, L. Metspalu, J. Jõudu and K. Jõgar

Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Kreutzwaldi St. 64, 51014 Tartu, Estonia; e-mail: kylli.hiiesaar@emu.ee

Abstract:

The adaptation of Colorado potato beetles (CPB) (Leptinotarsa decemlineata Say) to low temperatures has been the basis for the formation of a local permanent population in Estonia. The number of this pest fluctuates in different years on a large scale. The hibernation of the beetles in field conditions during the years 2000–2005 was observed and some factors influencing the beetles’ mortality was discussed in this study. Soil with a lighter texture – loamy sand proved better for the hibernation of CPB than clay loam soil with a heavier texture. 30 cm confirmed to be more suitable depth for hibernation than 50 cm, demonstrating lower mortality rate. Every autumn CPB populations were differently prepared for hibernation: part of the beetles burrowed themselves into the soil considered to be ready for over-wintering, and there were more survivals than among the beetles staying on the soil surface: that could not complete their maturation feeding. The temperature may become lethal for a majority of the hibernating population only during extreme winters when the temperature falls to -30^oC for a longer period of time. During our observation period, it happened only once: in 2002/2003. In more mild winters there were no problems with over-wintering: about two third of the beetles survived in clay sand and about a half in loamy clay soil. It is difficult to predict the annual damage caused by CPB because the Estonian population consists of adapted over-wintered beetles and beetles migrated from southern regions. In some years we have had a great number of immigrant beetles and, in some years, no immigration has occurred.

Key words:

Colorado potato beetles, mortality, overwintering, soil type