Assessment of the influence of fertilisation and environmental conditions on maize health

Field experiments showed the occurrence of such agrophages as the frit fly (Oscinella frit L.) and the European maize borer (Pyrausta nubilalis Hbn.). Identified diseases included fusariosis (Fusarium ssp.) and maize smut (Ustilago maydis Corda). The incidence of the frit fly was influenced by weather conditions, mainly temperature, in the period from sowing to the BBCH 15–16 phase. Moderate temperature conditions contributed to the occurrence of the pest. The significantly highest percentage of plants damaged by larvae of this pest was recorded on maize fertilised only with potassium (K) and phosphorus with potassium (PK). In turn, the lowest percentage of plants damaged by frit fly larvae was recorded for maize fertilised with nitrogen and potassium (NK). The percentage of plants damaged by the European maize borer was influenced by temperature and humidity conditions in individual years of the study. The highest percentage of plants damaged by larvae of the pest was found in the vegetation season characterised by the highest amount of rainfall with the lowest mean daily air temperature. The presence of potassium in a given fertiliser combination, the application of manure or combined application of manure and mineral fertilisation resulted in an enhanced resistance of maize plants to Fusarium ssp. fungi. The significantly greatest infestation of maize plants by the fungus Ustilago maydis Corda was recorded in the treatment in which only nitrogen was applied. In turn, the lowest percentage of plants with symptoms of this disease was recorded in the treatment with the application of potassium alone and in the application of potassium together with phosphorus.

Economic evaluation of biorational and conventional insecticides for the control of maize stem borer Chilo partellus (Swinhoe) in Zea mays

Maize borer, Chilo partellus (Swinhoe) is the chief limiting factor for higher corn production. Field trials to assess the efficacy of different insecticides against C. partellus were carried in district Ropar, Punjab. It was observed that significantly lesser leaf injury incidence was recorded in biorational treatment T1: chlorantriniliprole 18.5 SC (3.43 & 4.23) in comparison to broad spectrum conventional insecticide treatment T3: Deltamethrin 2.8 EC (4.63& 5.36) and T4 :Farmer’s practice 4.43 and 6.93. Whereas in plots with parasitoid application (T2), the leaf injury incidence was recorded to be 6.56 & 7.86 during 2012 and 2013, respectively. Though T2 was statistically superior to control, however it was not at par with insecticide treatments. Furthermore similar trend was observed for dead hearts reduction in different treatments. It was recorded to be 3.16 and 3.90, 3.33 and 3.96, 3.53 and 3.96 in insecticide treatment plots T1, T3 and T4 respectively. The economic returns on the basis of marketable grain yield in insecticide treated plots was more in T1 followed by T3 and T4 (51.99, 49.58 and 48.51) in comparison to control (40.44) and biological control plots (46.75). Therefore experimental data revealed overall superiority of biorational pesticide in comparison to conventional insecticides for reduction in pest damage and economic returns. Hence the option of biorational for the control of maize stem borer not only justify safety to environment but also offers effective control of borer population in maize ecosystem due to its distinct chemical class and unique mode of action.