Prophylactic disease control measures are to be undertaken against various diseases, just before the onset of southwest monsoon.Against abnormal leaf fall disease, 1% Bordeaux mixture or oil-based copper oxychloride (COC) is recommended.
For protecting young rubber and nursery plants repeated rounds of Bordeaux mixture sprayed through knapsack sprayer, rocker sprayer or high volume power sprayer are preferred.
For mature rubber, single round application of 1% Bordeaux mixture (3000 L/ha) may be sprayed. As an alternative, COC dispersed in agricultural spray oil is sprayed through micron sprayer from ground or helicopter, as aerial application. For micron spraying, the COC is mixed with oil in 1:5 proportion and 30-37 L/ha is sprayed. The machine should be carried through each row at a walking speed of 2-3 km/h. For helicopter spraying, 8 kg COC mixed with 40 L of oil is used. Fycop, Chlorocop, Parikh etc are oil-based COC powder formulations commonly used in rubber plantations. The spray oil is marketed mainly by Indian Oil Corporation. Care should be given to clean the spray equipment after each day’s use.
For shoot rot disease control in nursery and young field plants, 1% Bordeaux mixture is to be sprayed at 10-14-day-interval.
If monsoon sets in early and tapping is continued during rainy seasons, the tapping panel should be disinfected at weekly intervals with mancozeb (Dithane/Indofil M-45-5g/L) or phosphorous acid (Akomin/Phosjet 2ml/L).
Spraying of 1% Bordeaux mixture on the trunk also along with the spraying against Phytophthora leaf fall ensures reduction in pink disease incidence. In high disease-prone areas, Bordeaux paste can be applied prophylactically. For 2-year-old plants, the top most brown portion of all branches is to be applied with the paste in a 30 cm band in addition to the forking regions. For 3 year old plants, application has to be made on all major forking regions, except the lower most, and also on all leaders of topmost brown regions.
Spraying with 1 % Bordeaux mixture may be done on the tender green shoots and on the tender leaves of young rubber, to protect them against diseases like shoot rot, Phytophthora leaf fall etc. Since more leaves are emerging during this time in polybag plants in the nurseries, the disease may occur repeatedly in them. Hence, spraying with copper fungicides before the onset of south west monsoon coupled with repeated spray rounds during bright breaks is necessary. For ensuring proper sticking of the spray on tender foliage, stickers like Tenac, Teepol, Sandovit (@0.5 ml/L) may be added to the spray fluid.