49 

 d. Plants which destroy other weeds. 



The usual idea in cultivating plants between the Hevea, 

 is the destruction of noxious weeds. Passiflora foctida is 

 used accordingly, a plant which is found everywhere 

 at random. Especially on the flat low valleys, where 

 the struggle with the lalang is severest, this plant is 

 made much use of, but on no estate did I see it used 

 to protect the slopes against wash. It forms a rather 

 close cover over the soil, about i foot thick. The fall 

 of the leaves is not important, neither does it protect the 

 soil entirely against other weeds ; when the Passiflora 

 is taken away sometimes other weeds come up, amongst 

 which grasses are found, but amongst those, I never saw 

 Lalang. Although a climbing plant, it does not seem 

 able to climb the small Hevea trunks (see figs, icand 19.) 



Mimosa pudica (sensitive plant) is also used as a soil 

 covering against lalang, but it is not sufficient for this 

 purpose, it does not separate the soil sufficiently and raises 

 further the objection that it is extremely thorny, which 

 makes it very difficult for the coolies to walk in the grass. 



If a climbing plant is wanted for the destruction of 

 weeds, then "Kratok" (Phaseolus Lunatus], which is not 

 unfrequently planted in Java, for this purpose, will perhaps 

 give better results. As regards its growth and its capacity 

 to destroy other plants, it is not inferior to Passiflora. 

 Kratok, however, sheds fewer leaves and has the advan- 

 tage of enriching the soil with nitrogen and breaks up 

 with its deeply penetrating roots, the deeper layers of 

 soil. I saw it applied with considerable success to a Hevea 

 estate in Java, as a soil covering (see fig. 20.) 



The disadvantages oi all these weed destroyers are: 



