Iwaro, A.D., Sreenivasan, T.N. & Umaharan, P. 1998
Cacao resistance to Phytophthora: Effect of pathogen species, inoculation depths and pod maturity. European Journal of Plant Pathology, 104: pp.11-15
Notes
Trinidad - CRU, University of the West Indies Datafile: DIS_PHDS - Disease reaction to Phytophthora Descriptors: Resistance based on lesion size following inoculation with P. palmivora and P. capsici Environment: Inoculations were carried out using the stab technique at two depths (3mm and 9mm) Germplasm: 10 clones from the ICG, T collections Trinidad. Experimental Conditions: Pathogens were obtained from naturally infected pods of different cacao clones at UWI, Trinidad. Pathogens were then grown on pods of the same cacao clone (ICS 1) and re-isolated. Isolates were maintained on 20% V8 juice - calcium carbonate agar medium slants as stock and petri dish cultures were prepared for zoospore extraction. Zoospore suspensions were prepared from 10 days old cultures of P. palmivora and P. capsici by inundating each culture plate of 9cm diameter with 10ml of sterile distilled water (at 10 C), refrigerating for 25 min and incubating in the dark for 30 min. Zoospore concentration was determined by haemocytometer. Fully mature unripe pods were harvested from 10 selected clones and inoculated using the stab-3 or the stab-9 method. A standard injury was created on the pod surface using an apparatus that consists of 20 pins with a piercing length of 3 mm or 9mm. Inoculation was affected by placing a filter paper disk (4 mm diameter) immersed in zoospore suspension on the injured area and covered with a spot plaster. After inoculation pods were arranged in a completely randomised design with five replications. For control treatment treatment sterile distilled water was used instead of the zoospore suspension. Inoculated pods and controls were incubated at 25 C in trays lined with moist paper towels and covered with polythene film. After five days lesion area was assessed. Character Data: Wound: N=no, P=punch inoculation (4 mm hole), S3=stab inoculated to 3 mm depth, S9=stab inoculated to 9 mm depth.
Disease