Fungicidas na fisiologia e controle de doenças do milho

Abstract

The absence of culture rotation and the cultivation of the second corn harvest are factors that provide favorable conditions to corn leaf diseases. Actual studies demonstrate that aside from acting on the leaf diseases control, the strobirulins can have positive effects on many cultures´ physiological processes. Thus the objective of this work was to evaluate the fungicides actions on mixed formulations with azoxystrobin, picoxystrobin and trifloxystrobin in fungal diseases control and in physiological aspects in corn genotypes. The experiments were conducted on the Agrarian Sciences Experimental Farm (FAECA), in a vegetation house and in the Agricultural Microbiology and Phytopathology Lab, on the unit II of the Grande Dourados Federal University (UFGD), located in the county of Dourados – MS. Three tests were made, using different hybrids and comercial fungicides, being two of them field tests (summer harvest of 2017/2018; second harvest 2018) and one in a vegetation house. The tests were disposed in randomized blocks, in factorial scheme 3 x 4 (genotypes x treatments) with different comercial fungicides (strobirulins + triazoles) and a witness without application. Chlorophyll index and leaf area were evaluated for all the tests. On field testings the spot blotch and White spots were evaluated, aside from the following production atributes: grain yield (ton ha) and Thousand grain mass (g). After the evaluation, each grain portion was submitted to a sanitary quality analysis, doing a phylter paper test (“Blotter test”). At the vegetation house the SPAD index, gas Exchange and agronomic characteristics such as plant height (cm); green mass (g) and dry mass (g) were evaluated. The fungicide pycoxistrobin + cyproconazole provided a leaf area rise of 15,04% when compared to the treatment that didn´t receive a fungicide application in harvest period. The fungicide pycoxistrobin + cyproconazole, done 72 after the seeding, didn´t result in productivity rise even presenting 15,04% leaf area increase in summer harvest period.