Predac. fungi: 10 



with what happens in laboratory cultures. If one adds a small piece 

 of the fungus to a very vigorous eelworm culture, the fungus becomes 

 extremely predacious. IVhereas, if conversely, eelworms are added to 

 an active fungus culture, the fungus normally does not become preda- 

 cious. It does seem to me th8.t the presence of eelworms is a very 

 strong stimulus to the fungus to change it to the predacious form or 

 habit. I think that, in any fujrther work, the presence of organic 

 matter will have to be carefully considered. 



Another point, on which I would like to conclude, is this question of 

 the increase in eelworm populations as a result of the fungal treat- 

 ment. Obviously, we do not want to go about increasing eelworm popu- 

 lations. My own feeling is that this is not going to be too difficult 

 to get around. It seems to me that the most likely way is to increase 

 the period of predacious activity of the fungi. This could be done in 

 various ways. We have experimented with mixed cultures j mixing in a 

 ring-forming fungus which grows slowly with the more rapidly growing 

 reticulate types. If that can be done, and results have shown some 

 promise, I think that will much increase the period over which the 

 activity of the fungus can be spread. Another thing we are trying is 

 the use of dried fungus cultures. These have an uneven germination 

 period, thus, again spreading the time of application of the fungus 

 over a longer period. 



In regards to the question of applying so much inoculum that there is 

 difficulty in distinguishing between a manuring effect and the con- 

 trolling effect of the fungi, I am very much against putting in more 

 fungus than is necessary. There is a definite disadvantage to over- 

 doing. It goes back to the situation in the cultures where the fungus 

 is in excess of the nematode supply; the fungus won't remain in the 

 predacious condition. 



Actually, perhaps, what we should really be aiming at is not introducing 

 more organisms into the soil, but rather to change the soil so that 

 those beneficial organisms which are there become more active. These 

 would include all the predators of the nematodes, including fungi, other 

 nematodes, mites, and so on. I know this is what Lin.ford tried to do, 

 and I think it is very possible. 



(Editor's note): After Dr. Duddington mentioned that he would like to 



do some studies on the effect of luulching, several 

 observations were pointed out by participants in the workshop. In 

 Riverside, California, mulching has increased citrus nematodes in 

 citrus groves. Some early xTOrk on nematode control in tobacco, irorking 

 straw into the soil and making a bedding of the straw gave very effec- 

 tive control. Tea plantations in Ceylon are being brought back into 

 production by using a mulch for root-knot nematode control. One acre 

 is used to produce enough mulch grass to keep nine acres of tea plant- 

 ings going, and remarkable improvements have been noted after only a 

 couple of years. 



