Figure 1.

Crude polysaccharide (CPS) reduced infected leaves (%) and disease severity (%) in rubber tree leaves after infection by P. palmivora. Five grades of symptom (grade 0: No symptom; grade 1: Slight symptoms; grade 2: Medium distortion; grade 3: Rather serious distortion; grade 4: Extremely serious symptoms) were used to calculate the severity of infection (A). The percentage of infected leaves (B) and disease severity (%) (C) of rubber tree leaves after treatment with 0.5 mg/mL CPS and sterile distilled water (DW) for 24 h and subsequent inoculation with 1 × 10⁵ zoospores/mL of P. palmivora. The infected leaves and disease severity were monitored at five days post inoculation. Data bars were the means (± SE) of three replicates. Each replicate consisted of 42 independent leaves from seven independent rubber trees. One and two asterisks (* and **) indicate statistically significant differences of CPS-treated leaves compared with DW-treated leaves (P-value < 0.01 and P-value < 0.001, respectively) using Student’s t-test.