Resource Information
Resource Information |
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| Efficacy of Hot-Water Immersion Against the Taro Root Aphid, Hawaii, 1995 | |
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By: A. H. Hara, R.F.L. Mau, T. Y. Hata and B.K.S. Hu
Beaumont Agri. Res. Center University of Hawaii-Manoa 461 W.
Lanikaula Street Hilo, Hawaii 96720, Phone (808) 935-2885
HOST: CHINESE TARO: Colocasia esculenta
TARGETED PEST: 'Chinese' Taro root aphid: Patchiella reaumuri
(Kaltenbach)
EXPERIMENTAL PROCEDURE
Efficacy trials were conducted from 21 Apr through 24 Apr 95.
Taro hulis (0.5 inch cut stem with petiole attached) were
harvested from a infested field in Kaiwiki, Hi, (1,500 ft elev.)
placed in bags (three hulis per bag) made from Reemay crop cover
material, and transported in a cooler to the University of Hawaii
at Manoa Waiakea Experiment Station in Hilo, Hi. Roots and soil
were left on the hulis to maintain a sufficient test population.
Taro hulis (ca. 15 inches long x 2 5 inch base diameter) and
Reemay bags were immersed in 49 °C water from 0 to 5.5-min at 30
sec intervals. The bags were used to catch aphids which fall off
during treatment. Immediately following treatment, hulis were
cooled in a water bath at ambient temperature (26 °C) for a time
equal to the heating time then held in a dark room until
evaluation. The control was dipped in water at ambient
temperature for 30 sec. Three days after treatment, hulis were
dissected and the number of live and dead aphids counted.
RESULTS
Hot-water treatment at 49 °C for 5.0 and 5.5 min resulted in 100
% mortality of aphids on the taro petiole and roots,
respectively. Survivors were mobile and were usually found in
pockets between the dense roots. In actual commercial production.
hulis do not contain roots and soil.
Table 1 . Percent mortality of taro root aphids after hot-water
treatment at 49 °C.
| Treatment | Root | Petiole | Total |
| No Treatment | 5.8 (931)a | 9.8 (92) | 6.2 (1023) |
| Water Dip (Ambient) | 20.3 (989) | 9.7 (226) | 18.4 (1215) |
| 0.5 min | 0 4 (767) | 2.9 (173) | 0.9 (940) |
| 1.0 min | 35 3 (485) | 55.1 (89) | 38.3 (574) |
| 1.5 min | 73.0 (241) | 75.0 (80) | 73.5 (321) |
| 2.0 min | 89.0 (374) | 90.6 (32) | 89.2 (406) |
| 2.5 min | 64.7 (966) | 62.4 (311) | 64.1 (1277) |
| 3.0 min | 87.5 (376) | 77.8 (54) | 86.3(430) |
| 3.5 min | 94.7 (636) | 96.8 (63) | 94.8 (699) |
| 4.0 min | 99.8 (1112) | 100.0 (272) | 99.9 (1384) |
| 4.5 min | 95.8 (288) | 99.2 (131) | 96.9 (419) |
| 5.0 min | 99.2 (1705) | 100.0 (156) | 99.2 (1861) |
| 5.5 min | 100.0 (1511) | 100.0 (244) | 100.0 (1755) |
aNumber of aphids recovered.
PRECAUTIONARY STATEMENT
Use pesticides safely. Follow the pesticide label. Consult with
the Cooperative Extension Service or the Hawai'i State Department
of Agriculture for authorized special local need registrations or
additional information. The user is responsible for the proper
use, application, storage, and disposal of pesticides.
DISCLAIMER
Reference to a company or product name does not imply approval or
recommendation of the product by the College of Tropical
Agriculture and Human Resources, Cooperative Extension Service
University of Hawaii, or the United State Department of
Agriculture and does not imply its approval to the exclusion of
other products that may be suitable. All materials should be used
in accordance with label instructions or manufacturer's
directions.