Avaliacao de danos de percevejos e de desfolhadores em genotipos de soja de ciclos precoce, semiprecoce e medio | Evaluation of damage in soybean genotypes of three maturity groups caused by stink bugs and defoliators
2002
Lourencao, A.L. | Braga, N.R. | Miranda, M.A.C. | Valle, G.E. | Pereira, J.C.V.N.A. | Reco, P.C.
The damage of stinkbugs and defoliators in soybean genotypes was evaluated, under field conditions, at Taruma and Ribeirao Preto, State of Sao Paulo, Brazil. Three experiments, one for each of three maturity group, were carried out, in the 1997/98 and 1998/99 seasons. In Taruma, infestations of Diabrotica speciosa (Germar) and Cerotoma sp. occurred in both seasons and Anticarsia gemmatalis Hubn. in the second; in Ribeirao Preto, this caterpillar occurred only in the second year. Only in the first year in Taruma, stinkbug infestations [predominantly Piezodorus guildinii (West.)], fluctuated above the economic injury level (EIL); in Ribeirao Preto, the stinkbug infestations did not exceed the EIL. Defoliaton damage was estimated by the percentage of eaten leaf area (PAFC). Percentage of foliar retention (PRF) and yield were used to evaluate the stinkbug damage. Considering both years and both locations, among the early maturing genotypes (110 days), 'IAC-22' showed susceptibility to defoliators while 'IAC-17' confirmed its resistance to this group of pests as well as to stinkbugs. Among the genotypes of 120-day maturity group, IAC 93-3379 could be distinguished for the high yield, showing stability by this criteria. IAC 93-3275 and IAC 93-3237 presented low yield and high PAFC and PRF, mainly in Taruma. Regarding the genotypes of 135-day maturity group, susceptibility to stinkbugs was observed in 'IAC Holambra-Stwart', 'IAC PL-1' and IAC 87-2048; however, this line showed high yield under low infestation. Also, IAC 78-2318, IAC 93-1789 and IAC 93-1796 presented the lowest PRF, indicating to be less susceptible to this disorder.
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