Sugarcane borer Diatraea saccharalis (F.) is the primary sugarcane pest in Brazil.To estimate the relationship between larvae in sugarcane stalks and captures of male adults of D. saccharalis, we collected samples weekly: (1) adults with one delta trap with three virgin females and three female pupae and (2) larvae in 120 stalks per plot of 12.6 hectares (355 × 355 m).The study was conducted in two sites with five plots each, in the municipalities of Nova Ponte and Tupaciguara, Minas Gerais State, Brazil, from July 2016 to May 2017. Relationships between (1) males trapped per week and the number of larvae outside of stalks (LOS) were estimated and(2) we evaluated climate variables, namely average temperature, average relative air humidity, hours with relative air humidity below 30 %, rainfall and number of rainy days, and adults and larvae of D. saccharalis. We obtained generalized linear models for LOS in autumn and for larvae inside the stalks (LIS) in spring and autumn and trapped males in both sites. A significant and direct relationship between LIS and males trapped allows predicting larvae density based on captures of males. In addition, plant damage can be estimated based on accumulated captures of males. There was a negative relationship between hours of air humidity < 30 % and larvae outside of stalks. Densities of LIS can be estimated from male captures and by the humidity variables in the trapping week. Nevertheless, the models require validation in the field.
Sugarcane borer (Diatraea saccharalis) is one of the most important insect pests in sugarcane crops in Brazil. Historically, this insect has been controlled with releases of parasitoid Cotesia flavipes. However, chemical control with diamides and insect growth regulators has been used to help in control of this pest. In this study, the effectiveness of the diamide chlorantraniliprole applied in the sugarcane planting furrow and foliar spray on sugarcane borer damage and production were assessed. The experiment was carried out in an experimental area of SP80-3280 sugarcane variety, planted in November 2016 in Uberaba (Brazil), followed a randomized block design with four treatments: control, chlorantraniliprole foliar (21 g ha-1), chlorantraniliprole furrow (105 g ha-1), and chlorantraniliprole furrow (105 g ha-1) + foliar (21 g ha-1), with five replicates (plots). Each experimental plot had six planting lines of 10 m long spaced 1.5 m (90 m 2). One chlorantraniliprole application in the planting furrow and foliar spray was performed in November 2016 and in March 2017, respectively. All plots were infested with D. saccharalis eggs in February and March 2017. In May 2017, the plant height, stalk diameter, and number of tillers were assessed. In October 2017, the mass of stalks, sugarcane borer holes, number and percentage of damaged internodes were evaluated. Chlorantraniliprole applied in the planting furrow did not reduce the damage caused by D. saccharalis. The spray of chlorantraniliprole reduced the damage of the sugarcane borer in about 52%. The chlorantraniliprole application did not affect the initial sugarcane development or its production. One chlorantraniliprole spray in sugarcane was not enough to avoid the D. saccharalis damage and other additional control measures should be used.
Coffee seedling production in cone-shaped containers and substrate results in lower sanitary risk and costs. With the use of small containers and substrates with low fertilizer levels, fertigation is necessary for seedling development. An experiment was carried out with three macronutrient concentrations (electrical conductivities of 1.0, 2.0 and 3.0 dS m -1 ) and a non-fertilized control using Coffea arabica cv. Topázio seedlings in 50 cm 3 cone-shaped containers and composted pine bark-based substrate. The following fertilizers (expressed in g m -3 of water) were used in the nutrient solution with EC of 1.0 dS m -1 : Ca(NO 3 ) 2 (400), KNO 3 (250), MgSO 4 (175), (NH 4 )PO 4 (50) and ConMicros Standard ® (25). In the solutions with 2.0 and 3.0 dS m -1 , macronutrient concentration was doubled and tripled, while micronutrients remained the same. At four months we assessed EC and pH of the solution drained, shoot dry mass, shoot nutrient concentration and accumulation and macronutrient use efficiency. Fertigation with 1.0 and 2.0 dS m -1 produced seedlings with greater mass (+10%) than fertigation with 3.0 dS m -1 , while higher macronutrient supplies increased shoot N, P, K, Mg and S concentration. Fertigation with 2.0 dS m -1 caused greater shoot N, P, K and Ca accumulation and this conductivity also resulted in higher accumulation of B, Fe, Mn and Zn without increasing the micronutrient supply. The response to the increase in Ca in the nutrient solution is evident in the accumulation of this nutrient in the plant but not its concentration, possibly due to the dilution effect. Micronutrient accumulation in this species is also more adequate for determining nutritional status than the concentration in the plant. The least concentrated macronutrient solution increases nutrient use efficiency in C. arabica seedlings as well as being economically and environmentally more sustainable.
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