Changes in Soil Pest Populations Caused by Sugarcane Straw Removal in Brazil
The adoption of green cane harvesting system without burning has triggered the increase of pest infestations in sugarcane fields. This makes straw removal a promising alternative for pest control in sugarcane fields. However, further research is needed to understand the impacts of straw removal on pest infestation under field conditions. The objective of this study was to evaluate the incidence of root spittlebug (Mahanarva fimbriolata) and sphenophorus (Sphenophorus levis) under different rates of straw removal and contrasting edaphoclimatic conditions in the São Paulo state, southeastern Brazil. Eight field experiments were conducted throughout the sugarcane cropping cycle (two crop seasons) and were arranged in a randomized block design with four replicates. The experimental design included four straw removal rates: total removal, low removal, high removal, and no removal. The incidence of pests was evaluated during September and March (spring/summer seasons in the Southern Hemisphere) for root spittlebug and April to August (autumn/winter) for sphenophorus populations. Straw removal reduced root spittlebug infestation and this effect was more evident in clayey soils. The incidence of root spittlebug was three times higher in clayey soils compared to sandy soils. Straw removal did not influence sphenophorus population but reduced damages in sugarcane plants especially in clayey soils. The damage caused by sphenophorus was three times higher in clayey than in sandy soils. This study emphasizes that straw removal by itself is not a feasible strategy to control the root spittlebug and sphenophorus infestations in sugarcane cultivated areas of Brazil, thus an integrated management strategy should be a high priority.