Meiv South Wales. 179 



from other sections. The disease is now known to occur in North America 

 on a belt of land 130 miles wide, extending from Texas along the Gulf of 

 Mexico and Atlantic coast northward to the January isothermal of 50° Fah. 

 According to the best testimony yet obtained, the peach tree Ibrmcrly grew 

 on this area with no other disease than the borer, except in damp localities, 

 while now in many places, owing to the prevalence of root-gall, the trees 

 that do well are the exception. This fact shows how the disease has spread, 

 or at least increased, and should serve as a warning to Australians. 



In tlie United States the plants that have been found to be attacked by 

 Tylenchts arctiarms, the Australian worm, are as follows : — 



Badly effected. — Boots of cabbage, kale, potato, banana, radish, okra, pea, 

 peanut, cow-pea, bean, squash, pumpkin, melon, cucumber, tomato, beet, 

 plum, apricot, peach, almond, fig, English walnut, willow, gourd, bigonia, 

 sunflower, amaranth, dahlia, koniga, iberis, coleus, achyranthes, purslane, 

 sand-purslane, verbesina, worm- wood, Jerusalem-oak. 



SliglUli/ affected. — Roots of cotton, egg-jjlaut, pepper, spinach, cassava, 

 maize, orange, grape, mulberry, walnut, pecan, hibiscus, ice-plant, parlor ivy, 

 morning-glory, nolana, jjetunia, boussingaultia, spirea, flowering almond, 

 buddloia, cape jessamine, shepherd's purse, blackberry, dewberry, eupatorium, 

 cypress vine. 



These lists include the majority of the most useful food-plants, many 

 ornamental plants, and a number of the commonest weeds. Among the latter, 

 the roots of purslane, amaranth, Jerusalem-oak, and worm-wood, harbour the 

 greatest number of worms. 



The extent of the damage done by gall-worms is diflBcult to estimate. 

 Much land in Europe has become so badly infested that certain crops — for 

 example, sugar-beet — have had to be abandoned altogether. Not a beet-root 

 will mature. The plants break the ground, languish a few weeks, and then 

 die. Since time immemorial, crops of various kinds have died suddenly — 

 so suddenly, Dr. Neal remarks, as to justify the expression, "struck by 

 lightning." The unknown cause in some such cases has probably been the 

 gall-worm. Many an agricultural or horticultural failure attributed to the 

 use of improper fertilizer, to poor soil, or wrong cultivation, has been due to 

 this insidious foe attacking the very fountain-head of vegetation. "Were it 

 possible to sum up in pounds, shillings, and pence the damage done either 

 by T. arenarius or Scliachtii, the total would probably amount to a fortune 

 for a nation. 



Bemedies. 



All that can be done in combating root-gall must be directed toward 

 prevention. Once the gall-worm gains access to the roots, tlio game is up. 

 A leaf-destroying pest may be dealt witli even after its attack has made some 

 progress, but thus far, at least, roots and rootlets are inaccessible except at the 

 expense of the life of the plant. Hence it follows that all rational remedies 

 for root-gall must be directed either toward ridding the soil of the gall- 

 worms, or toward putting such obstacles in their way, or so reducing their 

 number, as to render their ravages bearable. These ends have been sought 

 in various ways : — 



1. By the use of some chemical, preferably a fertilizer, which will 



destroy the free-living larvai. 



2. By the selection of varieties not subject to root-gall. 



3. By trapping the worms and thus removing them mechanically from 



the soil. 



