Some short-term investigations into the management of vascular streak dieback disease on young cocoa Theobroma cacao in Giram Estate Sabah Malaysia

Manjit Sidhu, . Some short-term investigations into the management of vascular streak dieback disease on young cocoa Theobroma cacao in Giram Estate Sabah Malaysia. pp. 47-58. ISSN 0126-575X

Vascular Streak Dieback (VSD) disease is the most serious malady of cocoa in Sabah. In 1984 due to frequent and heavy rainfall the disease attained epidemic proportions making the establishment of nurseries and the field planting of cocoa extremely difficult. In view of the seriousness of the situation research was initiated to find immediate and longterm solutions to this problem. Cocoa seedlings can be raised successfully under polythene roof shelters which keep cocoa leaves rain-free denying fungal spores the moisture necessary for germination and infection. Another study confirmed previous findings that the earliest and most consistent symptom of VSD infection in young cocoa was a deformed chlorotic flush and the simultaneous appearance of raised lenticels on the stem. Symptoms can appear as early as six weeks after infection. Using this as a guide workers can be trained to detect infected material at an early stage thus preventing the build-up of inoculum in the nursery itself and reducing the amount of infected material being field planted. Five fungicide trials conducted over a period of 18 months revealed two new systemic fungicides (triadimenol and PP969) to be highly consistent in conferring protection against VSD infection. In nurseries foliar sprayings of both compounds at weekly and fortnightly intervals could provide 82-100 per cent seedling protection. In the field monthly soil drenches of triadimenol at 50-100 mg a.i. per seedling provided 95 per cent protection to 15-month old cocoa bushes grown in an environment of high VSD inoculum pressure. The cocoa being now well advanced in canopy formation and vigour was less likely to succumb to the disease.

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Abstract

Vascular Streak Dieback (VSD) disease is the most serious malady of cocoa in Sabah. In 1984 due to frequent and heavy rainfall the disease attained epidemic proportions making the establishment of nurseries and the field planting of cocoa extremely difficult. In view of the seriousness of the situation research was initiated to find immediate and longterm solutions to this problem. Cocoa seedlings can be raised successfully under polythene roof shelters which keep cocoa leaves rain-free denying fungal spores the moisture necessary for germination and infection. Another study confirmed previous findings that the earliest and most consistent symptom of VSD infection in young cocoa was a deformed chlorotic flush and the simultaneous appearance of raised lenticels on the stem. Symptoms can appear as early as six weeks after infection. Using this as a guide workers can be trained to detect infected material at an early stage thus preventing the build-up of inoculum in the nursery itself and reducing the amount of infected material being field planted. Five fungicide trials conducted over a period of 18 months revealed two new systemic fungicides (triadimenol and PP969) to be highly consistent in conferring protection against VSD infection. In nurseries foliar sprayings of both compounds at weekly and fortnightly intervals could provide 82-100 per cent seedling protection. In the field monthly soil drenches of triadimenol at 50-100 mg a.i. per seedling provided 95 per cent protection to 15-month old cocoa bushes grown in an environment of high VSD inoculum pressure. The cocoa being now well advanced in canopy formation and vigour was less likely to succumb to the disease.

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Item Type:	Article
Additional Information:	Ill.; 6 tables; 17 ref. Summary (En)
AGROVOC Term:	THEOBROMA CACAO
AGROVOC Term:	ENFERMEDADES FUNGOSAS
AGROVOC Term:	VIVEROS
AGROVOC Term:	SABAH/ SINTOMAS DE ENFERMEDADES (PLANTAS)
AGROVOC Term:	PLANTULAS
AGROVOC Term:	MORTALIDAD
AGROVOC Term:	FUNGICIDAS
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:54
URI:	http://webagris.upm.edu.my/id/eprint/18845

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