THRIPS CONTROL ON BANANA USING THE BUNCH INJECTION METHOD, 1998:

R. F. L. Mau and L. R. Gusukuma-Minuto

University of Hawaii CTAHR

Dept. of Entomology

3050 Maile Way, Rm. 310

Honolulu, HI 96822

Phone: (808) 956-7063

FAX: (808) 956-5888

e-mail: maur@avax.ctahr.hawaii.edu

 

L. Okayama

Aloha Farms, Inc.

Aiea, HI 96701

BANANA: Musa cavendishii

‘Williams Hybrid’

Hawaiian flower thrips (HFT);

Thrips hawaiiensis

Adult and nymph HFT infest and damage developing banana fruits during the immature inflorescence stage. Each inflorescence is covered by purplish-red scales and is composed of a succession of overlapping bracts that contain the flowers. Adults enter the pod-like inflorescence as soon as it emerges from the pseudostem and oviposit into the immature flowers. Adults and larvae feed on petals, developing fruit and the interior surface of the scales. Extensive feeding on the immature fruit results in corky, scab-like adhesions. Plant reaction to oviposition punctures results in permanent raised, pimple-like bumps. Extensive occurrence of either types of damage affects fruit marketability. Growers in other banana producing countries prevent flower thrips damage by making a single insecticide application into the pod-like inflorescence within 3-4 days after it appears.

Diazinon is the only insecticide registered for use in controlling thrips and the banana aphid in Hawaii. Several insecticides were tested for HFT control. Ten insecticide treatments were tested in collaboration with Aloha Farms, Inc. The test field was located at Mokuleia, Oahu, HI. Treatments were arranged in a completely randomized design with ten replications per treatment. Each tree was a single plant treatment replication. Treatment was accomplished by injecting 50 ml of spray mix into tip of the inflorescence using a compressed gas sprayer set at 30 psi. Post treatment observations were made at 15 DAT and at harvest (ca. 102 DAT). For the first observation, ten fingers from alternate hands were sampled from each bunch where the hand at the top of the bunch was counted as "Hand 1". The number of oviposition pimples was counted and recorded. At harvest an overall bunch damage rating, based on the severity and distribution of the pimples, was assigned ("0" = no damage, increasing as the number and distribution of the pimples increased to a maximum rating of "5").

Developing inflorescence treated with Provado produced banana fingers with the least amount of HFT oviposition damage. Success and Diazinon provided moderate control. Alert and AgriMek did not provide adequate protection.

Means in the same column followed by a different letter are significantly different (Tukey’s studentized range test; P<0.01); SAS for Windows version 6.12.

Means in the same column followed by a different letter are significantly different (Tukey’s studentized range test; P<0.01); SAS for Windows version 6.12.

¹"0" = no damage, increasing as the number and distribution of the pimples increased to a maximum rating of "5".