Banana (Musa AAA cv Williams) Response to Chemical and Biological Nematicides

The effect of the rotation of chemical and biological nematicide cycles per year on banana (Musa AAA cv. Williams) root weight, root nematode control and crop yield were compared in a commercial banana plantation in Costa Rica testing six treatments in a randomized complete block design with six replicates. Treatments consisted of the rotation of one, two or three chemicals or even the rotation of four biological nematicide cycles per year or the rotation of alternating chemical and biological nematicides in the year plus the untreated control. Averaging the 27 root nematode samplings after treatments application, the rotation of three chemical nematicide cycles by year reduced R. similis (P= 0.0005) by 44.5%, Helicotylenchus spp. (P = 0.0005) by 49.4% and total nematodes (P< 0.0001) by 45.3%. In contrast, the rotation of four biological nematicide cycles by year only drops not significantly R. similis by 6.9%, Helicotylenchus spp. by 9% and total nematode by 7.3%. Then, it seems that effective biological nematicides are not yet available for bananas, despite a substantial, positive literature on this topic. The number of uprooting plants was higher (P< 0.0001) in the untreated plots, with 101 during the experimental period, which would be equivalent between 161 and 188 uprooted plants by hectare that would end in a lost between 303 and 354 boxes by hectare by year. Even though in the second ratoon crop cycle, the rotation of three chemical nematicide cycles by year gave 308 more boxes per hectare (5.5 mt) than the untreated plots, the difference was not large enough to be significant (P= 0.2177). Difference in yield started at the third (P= 0.0405), and was increased at the fourth (P= 0.0009) ratoon crop, and final harvest (P= 0.0047), where the rotation of three chemical nematicide cycles be year improved yield by 506 (9.1 mt), 840 (15.2 mt) and 791 (14.3 mt) boxes by hectare by year, which resulted in a net profit (deducted the treatment cost and the packing cost of the additional boxes) of US $2,131; $3,743 and $3510 ha-1 year-1, respectively. Such improvement in yield, over the untreated plots, should be higher, because it did not consider the yield lost by uprooted plants.