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Epidemiology and Control of Rubber Black Stripe Caused by Phytophtora palmivora Butler
Thesis Abstract:
Experiments on epidemiology and control of rubber black stripe were conducted in 10 rubber plantations in Mindanao (Basilan, Zamboanga del Sur, North Cotabato, and Bansalan, Davao del Sur), Philippines, in June-September 1989. Experiments on development and control of black stripe were conducted at the University of Southern Mindanao and Philtread (Firestone) Rubber Plantations for three and two months, respectively. They were laid out in completely randomized design and two-factor treatments in randomized complete block design, respectively.
Black stripe was present in all rubber plantations. Disease incidence was relatively high in nine plantations, namely: Zamboanga Rubber Corporation, USM Rubber Plantation, Sandique, Martinez Rubber Corporation, Gallardo Farm, Glorianne, Firestone, Carbonell, and UP Land Grant. The lowest incidence was observed at Menzi Agricultural Corporation.
A survey revealed that black stripe severely affected Zamboanga Rubber Corporation while Sandi que, Martinez, and Gallardo Farm were moderately infected. The other six plantations were slightly infected.
Factors that appeared to have contributed to the variation in disease severity at each plantation were climate, population density, topography, vegetation, crop protection practices, fertilization, and pathogenicity of the isolates.
Preliminary results on the assessment of the disease before tapping of rubber showed a high increase in severity. Moreover, percentage of disease severity was higher in mature (10-20 years old) than immature rubber (6-1 0 years old).
Disease severity increased from June to September, with slow rate of infection. Temperature and relative humidity appeared to have minimally affected the development of black stripe as shown by multiple regression. Rainfall did not affect disease severity.
In vitro studies revealed that metalaxyl at 7 tbsp/20 Land captafol at 16 tbsp/16 L were highly effective in controlling black stripe.
Field experiments showed that after 30 and 60 days, metalaxyl, captafol, and oxadixyl + mancozeb effectively controlled black stripe when applied once a week. Fungicides did not affect latex production or caused panel dryness of trees.
