Integrated pest management in Chinese kale (Brassica oleracea L. var. Alboglabra Bailey) using selected pest repellent plants and biopesticides | |
| Author | Supawan Kianmatee |
| Call Number | AIT Diss. no.AS-06-08 |
| Subject(s) | Pests--Integrated control Cole crops |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Agricultural Systems and Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AS-06-08 |
| Abstract | Chinese kale (Brassica oleracea L var. Alboglabra Bailey) is one of the most commonly consumed and heavy pest attractive vegetable in Thailand. Synthetic pesticides are frequently and heavily applied on Chinese kale to control insect pests. This often leads to resistance development in pests, secondary pest outbreaks, pollution of the overall environment, and health hazards to people. This study was conducted to assess the potential of pest repellent plant (PRP) species to reduce insect pests in Chinese kale and to develop and integrated pest management (IPM) strategy by integrating both effective PRPs and biopesticides in order to minimize the use of highly toxic synthetic pesticides and their residue in food and environment. A series of experiments aiming at three approaches, viz. screening of PRPs, integration of selected PRPs with Chinese kale in intercropping, and integrating PRPs and biopesticides for an IPM strategy, was conducted at the Agricultural Systems and Engineering Research Farm at the Asian Institute of Technology, Thailand during December 2004 - March 2006. In the first experiment, fourteen PRPs, viz. marigold-Fl hybrid (Targetes erecta L.-Tl), Angelonia (Angelonia goyazensis Benth -T2), tomato (Lycopersicon esculentum Mill.-T3), garlic (Allium sativum L. var. Sativum-T4), onion (Allium cepa L. var.Cepa-T5), hot pepper (Capsicum frutescencs L.-T6), coriander (Coriandrum sativum L.-T7), citronella grass [Cymbopogon nardus L. (Rendle)-T8], lemon grass [Cymbopogon citratus (DC) Stapf-T9], mint (Mentha cordifolia L.-T10), sweet basil (Ocimum basilicum L.-T11), hoary basil (Ocimum citratum L.-T12), sacred basil (Ocimum sanctum L.-T13), and stink weed (Eryngium foetidum Linn.-T14), with a control (without PRPs) were evaluated for their performance in repelling insect pests attacking Chinese kale in a randomized complete block design (RCBD) with 2 replicates. The results showed that common insect pests infested during the growing period in Chinese kale were diamondback moth (DBM) [Plutella xylostella (Linnaeus)], common cutworm (CCW) [Spodoptera litura (Fabricius)], cabbage webworm (CWW) [Hellula undalis (Fabricius)], beet armyworm (BAW) [Spodoptera exigua (Hubner)], cabbage looper (CBL) (Trichoplusia ni Hubner), flea beetle (FBT) (Phyllotreta sinuata Steph.) and cabbage aphid (CBA) [Lipaphis erysimi (Kaltb.)]. The insect pests varied with the PRP and the growth stage of the crop. Citronella grass was the best repeller for DBM larvae, while hot pepper and Angelonia were excellent in repelling CCW larvae. The PRPs that repelled CWW larvae were sweet basil, coriander, citronella grass, mint and sweet basil. Sweet basil, hoary basil, coriander, mint and citronella grass showed excellent repellence on BAW larvae. Angelonia, citronella grass, sweet basil and sacred basil were effective pest repellent plants for FBT adults. Furthermore, CBA was effectively repelled by tomato and hot pepper. The results also showed that some PRP species have the potential of maintaining a range of pest-free distance. The second experiment was conducted to develop intercropping patterns for Chinese kale with PRPs. Seven PRP species selected from the first experiment (viz. Angelonia, tomato, hot pepper, coriander, citronella grass, sweet basil and sacred basil) were arranged as an intercrop with Chinese kale providing 2m inter-rows and 1m intra-rows, and assessed the performance of each intercrop using insect pest counts and pest-free distance, in a RCBD with three replicates. An additional plot containing Chinese kale alone (without any PRP species) was added as a control treatment. The result showed that Chinese kale associated with sacred basil had the lowest number of both FBT and CWW, while citronella grass had the lowest number of CCW, Diamondback moth was reduced by all PRPs, except in hot pepper, but the difference was not significant. At the harvest, the lowest pest damage (35%) and the highest quality of yield with a mean quality score of 1.9 were in plots associated with sacred basil, followed by citronella grass (36.7% and 2.3, respectively) and sweet basil (53.3% and 2.5, respectively), and hence these three plants were used for the third experiment. The third experiment aimed at developing an effective and sustainable IPM strategy, and three best performing PRPs [viz. citronella grass (CG), sweet basil (SwB) and sacred basil (SaB)] were integrated with two biopesticides [viz. Bacillus thuringiensis (Bt) and neem extract (Azadirachta indica)], and a control plot (without PRP or biopesticides) were tested in RCBD with 3 replicates. The results showed that DBM density was lowest in CG alone, CG + SaB, SwB + biopesticides and SaB + biopesticides, while it was the highest in the control. The densities of CCW, CWW, SAW, CBL, FBT and CBA were not significantly different among treatments. The lowest pest damage and the best quality of yield of Chinese kale were in CG + biopesticides treated plots. SwB + biopesticides treated plots had the highest partial net return of US $ 10,534 per ha, followed by CG + biopesticides (US $ 10,323 per ha), and biopesticides alone (US $ 10,260 per ha). The results of the overall study showed that the biopesticides alone were ineffective in controlling the pests in Chinese kale. The combination of all three PRPs, i.e. CG, SaB and SwB was also inferior to individual PRPs when combined with biopesticides in terms of percent damage, fresh weight and mean quality score, except that partial net return was slightly lower in the SaB + biopesticides. Accordingly, both SwB + biopesticides and CG + biopesticides were superior to others in the overall performance, and hence recommended for pest management in Chinese kale. Use of these two combinations would help minimize the application of highly toxic synthetic pesticides and their residue in food and environment. |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AS-06-08 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Aquatic Systems(AS) |
| Chairperson(s) | Ranamukhaarachchi, S. L.; |
| Examination Committee(s) | Athapol Noomhorm;Preeda Parkpian;Ooi, Peter;Joshi, R. C.; |
| Scholarship Donor(s) | Ministry of Agriculture and Cooperatives, Thailand;Asian Institute of Technology Fellowship; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2006 |