RESUMO
Understanding sugarcane (Saccharum spp.) response to multiple pest injury, sugarcane borer (Diatraea saccharalis) and spittlebug (Mahanarva fimbriolata), is essential to make better management decisions. Moreover, the consequences of both pests on the sugarcane raw material quality have not yet been studied. A field experiment was performed in São Paulo State, Brazil, where sugarcane plants were exposed to pests individually or in combination. Plots consisted of a 2-m long row of caged sugarcane plants. Photosynthesis was measured once every 3 months (seasonal measurement). Yield and sugar production were assessed. The measured photosynthesis rate was negatively affected by both borer and spittlebug infestations. Photosynthesis reduction was similar on plants infested by both pests as well as by spittlebug individual infestation. Plants under spittlebug infestation resulted in yield losses and represented 17.6% (individual infestation) and 15.5% (multiple infestations). The sucrose content and the sucrose yield per area were reduced when plants were infested by multiple pests or spittlebug.
RESUMO
O controle microbiano de Mahanarva fimbriolata é de suma importância para o manejo dessa praga em cana-de-açúcar, porém carece de melhorias quanto à tecnologia de aplicação. O trabalho teve como objetivo definir um modelo de bico de pulverização adequado para o controle de M. fimbriolata, com base no padrão de distribuição de calda aspergida e espaçamento entre bicos. Utilizaram-se os bicos TF4, TTI e AIUB11004VS e caldas a base de fungo Metarhizium anisopliae sem adjuvante e com Agral a 2% e 4%. Avaliou-se o espaçamento entre bicos baseado na construção de curvas de deposição, considerando CV máximo de 10%; ângulo de abertura e vazão dos bicos. Os maiores espaçamentos foram de 85cm em calda com 2% de adjuvante para o bico TF4, 70cm para AIUB11004VS sem adição de adjuvante e 55cm para o bico TTI, independente da calda. Em relação ao ângulo de abertura, houve apenas diferença entre os bicos testados em uma mesma calda. A vazão foi maior para a calda com 4% de adjuvante para os bicos TF4 e TTI, sendo que AIUB11004VS apresentou menores vazões em relação aos outros modelos para calda com 2% e 4% de adjuvante. Conclui-se que o modelo AIUB11004VS é uma importante ferramenta operacional, visando o controle de M. fimbriolata, por apresentar menor consumo de calda e bons resultados de distância entre bicos.
The microbial control of Mahanarva fimbriolata is very important to management of this pest in sugarcane crops, however lacks improvement in spraying technology. The work aimed to evaluate a nozzle model adequate to control M. fimbriolata, based on pattern of spray distribution and the space between nozzles. TF4, TTI and AIUB11004VS nozzles containing the fungus Metarhizium anisopliae without adjuvant, with Agral 2% and 4% were used in the assay. We evaluated spacing between nozzles by constructing deposition curves considering maximum CV of 10%, spray angle and nozzle flow for different sprays. The larger nozzle spacings were 85cm for spray with 2% of adjuvant and TF4 nozzle, 70cm for AIUB11004VS without adjuvant addition and 55cm TTI nozzle, independent of spray used. Despite the spray angle, we observed difference between the nozzles to the same spray. The flow was larger for spray with adjuvant at 4%, to TF4 and TTI, while AIUB11004VS showed minor flows when compared to the others nozzles using 2% and 4% of adjuvant. By presenting good results of distance between nozzles and minor spray consumption, AIUB11004VS is a good tool for control of M. fimbriolata.
RESUMO
In order to assess the effectiveness of Metarhizium anisopliae var. anisopliae (Metschnikoff) Sorokin isolates in controlling the sugarcane root spittlebug Mahanarva fimbriolata (Stal) (Hemiptera: Cercopidae), nine isolates obtained from a single geographical region were studied. 'Confirmed cumulative' and 'corrected cumulative' spittlebug mortality rates were measured for each of the isolates. Based on the confirmed mortality curve, the isolates URM5946, URM5951 and URM6033 were considered to be potentially the most effective in a biological control program for M. fimbriolata.
