Influence of the sowing data concerning maize leaf weevil (Tanymecus Dilaticollis Gyll) attack in atypically climatic conditions from spring period, in South-East of Romania

Abstract

Maize leaf weevil (Tanymecus dilaticollis Gyll) is main pest of the maize crop in south and south-east of the Romania. Every year, more then one million of hectares sowed with maize are attacked by this pest. Climatic conditions registered in April and May, between 2016 and 2018, at NARDI Fundulea, was atypically for this pest attack. In years 2017 and 2018, rainfalls amount was over multiyear averages, both in April and May, while average air temperature was lower then multiyear average, in May (years 2016 and 2017) and April, year 2017. Registered rainfalls amount in April and May, in year 2018 were lower while average air temperatures were higher then multiyear average. At NARDI Fundulea, it has studied maize sowing data influence, in period 2016-2018, concerning maize leaf weevil attack at maize plants in first vegetation stages (BBCH 10-BBCH 14). In the climatic conditions of the year 2016, the attack of the T. dilaticollis weevils was higher at untreated maize plants sowed on 27 April (I=6,01) comparative with untreated maize plants sowed on 19 May (I=5,85), but statistical differences weren’t significant (p<0.05). In the climatic conditions of the year 2017, the attack of the T. dilaticollis weevils was higher at untreated maize plants sowed on 19 May (I=5,68) comparative with untreated maize plants sowed on 27 April (I=5,30), but statistical differences weren’t significant (p<0.05). In the climatic conditions of the year 2018, the attack of the T. dilaticollis weevils was higher at untreated maize plants sowed on 25 April (I=4,61) comparative with untreated maize plants sowed on 17 May (I=4,16), in this case statistical difference was significant (p<0.05). In case of variants with treated seeds with imidacloprid active ingredient, it hasn’t registered significant statistical differences concerning attack intensity between plots sowed in April and plots sowed in May. In all studied years, differences between untreated variants and variants with seed treated with imidacloprid active ingredient, was significant from statistically point of view (p<0.05), regardless sowing data.