266 



PHYTOPHTHOPvA MEADII n. Sp. ON HEVEA BRASILIENSIS 



(a) Different concentrations of izal in French-bean-agar tubes were 



made up and autoclaved. 



(b) Different concentrations of izal made with sterile water were added 



to liquid French-bean-agar tubes that had been autoclaved in 

 order to make definite concentrations of izal in the French- 

 bean-aaar. 



Concentration 



1% 



n-5% 

 0-1% 

 n-01% 



0-001% 



French-bean-agar 

 izal in French-bean-agar 



(a) 



14 tubes. 



Good growth in 



all tubes. 



No growth. 



ditto 



ditto 



ditto 



(b) 



6 tubes. Good growth in all 



tubes 



7 ,, No growth 

 7 

 8 

 7 



8 ,, Growth in 2 tubes. 

 Growth in 3 tubes. 



Different concentrations of izal in water were made, and in no case of 

 O'l per cent, or above did the mycelium grow or sporangia discharge. Izal is 

 thus a powerful fungicide so far as this fungus is concerned, and can be used 

 in dilutb solutions. As, however, it is to be apphed in the monsoon, a consider- 

 ably more concentrated solution is required, and 5 per cent, is the usual strength 

 used on estates. The ordinary conical kitchen lamp makes a good receptacle, 

 and the slightly projecting wick drawn along the tapping cut leaves a thin 

 film of the izal solution. Other investigators have tried izal and other similar 

 substances, and recommended as preventives 10 per cent, izal, 20 per cent, 

 carbolineumj 20 per cent, brunolinum or 50 per cent. Jodelite to be applied 

 as frequently as tapping is done. I have also found that the distillate from 

 coconut-shells charred in a closed chamber (earthenware pot) even in solutions 

 of O'l per cent, prevents the growth of the fungus in culture ; but its effect in the 

 fieM has not been tested yet. This is of some interest at the present time, 

 when the other substances are expensive and not easy to get. 



I have seen folded strips of gunny tied round the trunks of trees in a 

 slanting direction with good results. The rain-water streaming down the 

 trunk was guided along the gunny, and caused to run down the side of the tree 

 away from the cut. The bark below the gunny in the region of the tapping 

 surface remained comparatively dry as long as the gunny remained tight. 

 This wsts being tried from the point of view of preventing flooding of the cups 

 during heavy rain, and it is a sound idea and well woith developing from the 

 point of view of bark-rot. Something cheap and just good enough to last 

 for the rainy months, and then not worth the trouble of keeping till the next 



