18 Journal of the Department of Agriculture. — July. 1922. 



throiig'li being laid down with infested seed potatoes or tlirougli the 

 wash over them of infested soil by storm or irrigation water. Once 

 infested, lands will remain so as long- as plants or weeds favoured 

 by the worms grow upon them. There is really no end to the list 

 of plants in the roots or tubers of which gall worms may not flourish. 

 Very few plants appear to be quite immune. The following 

 are never, or at least very seldom, attacked: — 



(1) The velvet bean and several species of the genus to Avhicli 

 it belongs. 



(2) Many glasses, sucli as crab, red-to]), and Johnson grass. 



(3) The millets. 



(4) Some varieties of oats and barley. 



(5) Maize, wheat, kaffir corn, sorghum, rye, and timothy. 



In dealing' with this pest, prevention is far better than cure. 

 It should be the practice of every farmer or small holder to keep a 

 most searching and careful watch for any indication of this trouble. 

 Seed potatoes especially sliould be carefully looked over before 

 planting; and only clean, smooth seed should be sown. The field 

 into which a crop is to be planted should be inspected to see if 

 weeds or other plants thereon are not perchance harbouring the pest. 

 This is a most important point, and if carefully observed may save 

 much future trouble. 



There is no entirely satisfactory treatment for lands bearing 

 perennial crops. However, any cultural method that encourages 

 deep rooting on the part of the attacked crop will help. For land 

 infested with gallworms, and not bearing a perennial crop, the 

 following methods may be recommended : — 



(1) Keeping the land free from vegetation of all kinds for two 

 years. No crop, no Aveeds, no plant of any description must be 

 tolerated; in other words, absolutely bare fallow must be practised. 

 This is a most effective method, but it is not very practicable. 



(2) Planting the land to non-susceptible crops for at least two 

 (perhaps better three) years, using in the winter small grains, such 

 as wheat, rye, or oats, and in the summer the velvet bean, Florida 

 beggar weed, the iron cowpea, or even peanuts (monkey-nuts), and 

 scrupulously destroying all weeds that might harbour gallworms. 



(3) Making heavy applications of fertilizers, especially those 

 containing potash, except where the soil already contains this in 

 abundance. This treatment often reduces gallworm injury greatly. 



(4) Where possible, flooding the land for a period of some weeks. 



(5) Where rain is not likely to interfere, ploughing, and allow- 

 ing the soil to dry out for several months. 



(6) Preventing, by the use of embankments, ditches, etc., the 

 washing of soil from infested fields to the field which it is desired 

 to free from the pest. The introduction of the pest by tools, wagons, 

 farm animals, etc., should be avoided. 



Where it is desired to put down seed beds for tobacco, tomato, 

 and the like, an atteinpt may always be made to free the top soil 

 of these creatures. The soil should be loosened, and then roasted 

 by maintaining over it for some time a vigorous fire of brushwood. 



