Preliminary study concerning climatic conditions influence from winter season on maize leaf weevil (Tanymecus dilaticollis Gyll) attack

Abstract

Maize leaf weevil (Tanymecus dilaticollis Gyll) is the main pest of the maize crops in south and south-east of the Romania. In this paper, authors collective present preliminary results of a study concerning influence of the winter conditions on attack of T. dilaticollis. It has analyzed the temperatures from winter (December-February) and attack intensity of the studied pest at maize untreated plants, in spring period. Pest attack was rated when maize plants were in four leaf stage (BBCH 14) on a scale from 1 (plant not attacked) to 9 (plants complete destroyed). During the time, at NARDI Fundulea, winters were variable, from one year to another. The attack of T. dilaticollis at maize untreated plants registered in springs followed after cold winters was low in 1999 (I=4.3), high in 2003 and 2012 (I=7.8 and 6.7) and moderate in 2011 (I=5.8). The attack registered in springs followed after warm winters was high in 1989 (I=9.0) and 1995 (I=8.4), while in year 2001, followed after one of the warmest wither of the century, the attack of the maize leaf weevil at untreated plants was low (I=4.8). There were no correlation between temperatures registered during winter season and attack of T. dilaticollis at maize plants registered in spring. The most important for pest attack are the climatic conditions from period when maize are in first vegetation stages (BBCH 10-14). Results of the study effectuated at NARDI Fundulea make in evidence that low rainfalls level and high temperatures from this period favor pest attack.