Impact of Fungicide Spray Timings on Foliar Diseases Control in Wheat Cultivars

Wheat (Triticum aestivum L.) is grown throughout the winter time in Southern Brazil and turns out to be the main agricultural crop at such a year season in the State of Paraná. However, throughout the crop growing season foliar diseases significantly compromise commercial yields in such a manner as to justify the application of fungicides at the right time to control foliar diseases in production fields. The aim of the current manuscript was to assess the impact of different timings for fungicide application (epoxiconazole + pyraclostrobin) on the control of leaf rust (Puccinia triticina E.) and yellow spot (Pyrenophora tritici-repentis) diseases in two wheat genotypes featured by distinct levels of susceptibility in Southern Brazil. A field trial was conducted in Ponta Grossa, State of Paraná, Brazil, in light of split plot statistical design at an experimental area belonging to CESCAGE. The following treatments were imposed in the current study: control (with no sprays);sprays at the first node, booting and heading;sprays at stem extension and flowering;sprays at booting and heading. Throughout the entire crop growing season, the control treatment was conducive to the highest severity levels for both diseases. The increasing of the area under the diseases progress curve assessed herein substantially impinged upon yield components of both wheat genotypes under scrutiny. In general, fungicide sprays at the first node did not culminate in economical advantages. The best timing for fungicide application was the one ascribed to booting and heading stages.

Do Aqueous Extracts from Buckwheat Compromise Seed Germination and Initial Development of Bidens pilosa and Euphorbia heterophylla?

Fagopyrum esculentum Moench (buckwheat) is a dicot species from the Polygonaceae family used as a cover crop in agricultural systems featured with a remarkable allelopathic potential for weed control, helping herbicide-resistance management and promoting substantial reductions in herbicide applications. The aim of this research was to examine the allelopathic potential of aqueous extracts from seeds and aerial part of buckwheat on seed germination and initial development of Bidens pilosa and Euphorbia heterophylla. Bioassay experiments were conducted under a completely randomized experimental design with four replications, containing 50 seeds each. Both weed seed species were harvested in a soybean field, and seed viability was previously assessed. Seeds were exposed to four concentrations (0, 25, 50, and 100%) from extracts of seeds (ES) and aerial part (EAP) of buckwheat. Germination speed index (GSI) in B. pilosa and E. heterophylla was daily evaluated throughout 14 and 16 days, respectively, whereas percentage of germination, abnormal seedlings, as well as non-germinated seeds, root (RL) and aerial part length (APL), and total dry matter (TDM) were rated at final germination test. EAP reduced the GSI, especially under the 100% concentration. Germination percentage was lower and abnormal seedlings increased for both weed species when seeds were exposed to EAP concentrations greater than 25%. However, ES did not impinge upon E. heterophylla germination. EAP and ES reduced the APL, RL, and TDM for concentrations greater than 50%, except for ES which did not affect E. heterophylla development. Both extracts from buckwheat have a high capacity to inhibit germination and compromise seedling development, culminating in such a potential alternative for B. pilosa and E. heterophylla management in agricultural systems.