title: Effects of nitrogen and potassium combinations on yields and infestations of maize by Busseola fusca (Lepidoptera: Noctuidae) in the humid forest of Cameroon.
abstract: Field trials were set up in the humid forest zone of Cameroon to investigate the effects of combinations of different rates of nitrogen (N) (0, 60, and 120 kg N ha(-1)) and potassium (K) (0, 80, and 160 kg K ha(-1)) applied to the soil on the incidence and damage of the noctuid stemborer Busseola fusca (Fuller), and on maize, Zea mays L., yield. Each N/K combination had an insecticide control to assess yield losses due to borers. In contrast to N, K had no effect on plant growth and borer incidence and damage. Across seasons and days after planting, total plant dry matter (DM) production increased with N level and it was 1.2-1.9 and 1.7-2.2 times, respectively, higher at 60 and 120 kg N ha(-1) compared with 0 kg N ha(-1). Total DM at harvest was strongly related to the N content of the plant at 63 d after planting. At the early growth stage, borer abundance and stem tunneling tended to increase with N level, but percentages of dead hearts did not vary with treatment. Maize grain yields increased linearly with N level, but grain yield losses decreased depending on season. Grain yield losses were 11-18.2 times higher with 0 kg N ha(-1) compared with 120 kg N ha(-1). The findings so far indicated that, soil application of N improves the nutritional status of maize, which consequently enhanced its tolerance to stemborer attacks. Improving soil fertility can thus be a very effective means of complementing integrated stemborer control in the humid forest zone of Cameroon.
authors.affiliation: Institut of Plant Diseases and Plant Protection, Herrenhäuser Str. 2, 30419, Hannover, Germany. achabi@icipe.org
authors.forename: Adenirin
authors.initials: A
authors.lastname: Chabi-Olaye
authors.forename: Fritz
authors.initials: F
authors.lastname: Schulthess
authors.forename: Christian
authors.initials: C
authors.lastname: Borgemeister
mesh_terms: D000383:Agriculture; D000818:Animals; D002163:Cameroon; D004305:Dose-Response Relationship, Drug; D005308:Fertilizers / Q000032:analysis; D006813:Humidity; D007915:Lepidoptera / Q000254:growth & development*; D009584:Nitrogen / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D012621:Seasons; D012987:Soil / Q000032:analysis*; D014197:Trees; D014329:Tropical Climate; D003313:Zea mays / Q000254:growth & development / Q000378:metabolism / Q000469:parasitology*
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen; D011188:Potassium