Soybean [Glycine max (L.)], one of the most important crops in Argentina, is commonly infected by Colletotrichum truncatum, the causal agent of anthracnose. Tagetes filifolia essential oil (EO) is presented as a natural approach to minimize the dose of chemical fungicides applied to the crop. The fungus Trichoderma harzianum is used as a biocontrol agent because of its ability to produce secondary metabolites that destroy cell walls of phytopathogenic fungi. However, its performance can be affected when it is exposed to chemical fungicides. The objective of this work was to evaluate the antifungal activity of T. filifolia EO both individually and combined with chemical fungicides against C. truncatum, and its effect on T. harzianum. Fungi were isolated from soybean crops. The following pesticides were assessed: carbendazim (F1), difenoconazole (F2) and trifloxystrobin + cyproconazole (F3). The EO was obtained from native plants and its chemical composition was analyzed by gas chromatography–mass spectrometry (GC–MS). The minimum fungicide concentration (MFC) was determined for each compound. Fungicides were combined with the EO to look for combinations that allowed a reduction of pesticide doses. Among fungicides, F1 showed the strongest antifungal activity against C. truncatum (MFC = 0.25 μl ⋅ l–1) and T. harzianum (MFC = 1.5 μl ⋅ l–1). The sensitivity of both fungi to the EO was lower than to fungicides. The EO presented MFCs of 6,000 and 9,000 μl ⋅ l–1 against C. truncatum and T. harzianum. The EO and F1 affected the growth of T. harzianum at concentrations that controlled C. truncatum (31 and 10%). Eight combinations of fungicides and the EO allowed fungicide concentration reductions of up to 80%, although the growth of the biocontrol strain was also affected. The results demonstrated that T. filifolia EO can be used to control anthracnose and reduce doses of chemical fungicides applied to soybean crops. Its effect on T. harzianum should be considered in the design of integrated pest management strategies.
CropSyst model can be used as irrigation water management tool to increase wheat productivity with poor quality water. The objective of this study was to calibrate CropSyst model for wheat irrigated with fresh and agricultural drainage water. To do so, three field experiments were conducted during three successive seasons in Nubaria Agricultural Research Station, Egypt representing the newly reclaimed calcareous soils. In the first season the treatments were 100% crop evapotranspiration (ETc) of fresh water (FW) and 100% ETc of agricultural drainage water (DW), while in the second and the third seasons, the treatments were 100% ETc of FW, 100% ETc of DW, 120% ETc of DW and 130% ETc of DW. From these results one can concluded that deducting 5% of the applied water to all treatments reduced yield by 3, 5 and 7% in the first, second and third growing season, respectively as a result of heat stress existed in the 2nd and 3rd seasons during reproductive phase. Furthermore, deducting 5% of the applied water from all treatments in the vegetative phase only resulted in lower yield losses. Thus, using CropSyst model could guide us to when we could reduce the applied irrigation water to wheat to avoid high yield losses.