Vol. IX. No. 201. 



THE AGRICULTURAL NEWS. 



11 



FUNGUS NOTES. 



SOME FUNGOID DISEASES pP GARDEN 

 PLANTS. i 



It is hoped that the following geAeral remarks, on 

 the methods of treating some of the diseases of garden 

 plants, may prove of value to those who are interested 

 in the cultivation of flowering plants, palms and other 

 ornamental plants. 



All fungoid diseases of garden plants may be cla.ssified 

 under the three following heads : — 



1. Root diseases. 



2. Leaf and green stem diseases. 



3. Disease.? of hard woody stems. 



Each of these classes of disease hasi its own general 

 methods of treatment. 



ROOT DISEASES, The external symiitoms of root disease 

 usually bear a close resemblance to those shown when a plant 

 is suffering from drought. If the disease spreads slowly, the 

 lower leaves are seen to wilt, dry up at^ their edges, and 

 hnally fall off; gradually more and more of the leaves 

 fall in this way, until none are left,' and the plant 

 is dead. If, however, the disease spredds quickly, the 

 symptoms are somewhat different. One 'morning it may 

 be observed that all the leaves of the plant look soft and 

 limp, as if it had not been watered. On the next day, .some 

 of the lower leaves are beginning to dry up, and all of them 

 are considerably wilted; by the next after, the plant is dead. 

 It is a simple matter to determine whether the plant is really 

 suffering from drought or from a root disease; for if the 

 wilting is due to drought, the plant will recover on being 

 watered, but if the roots are diseased, watering will be with- 

 out effect. On pulling up a plant that has died of a root 

 di.sease, the roots are often seen to be covered with a fine 

 white web, which is the mycelium, or vegetative portion, of the 

 fungus causing it. This web will spread in the soil from the 

 diseased plant to its healthy neighbours, but there will be no 

 signs of this until the formerly healthy plants are themselves 

 so badly attacked that nothing can be done to save them. 



In nearly all the West Indian islands, a particularly 

 ■destructive root fungus occurs, which destroys Aroids, 

 Antirrhinums, Tomatos and several other plants. 



When a root disease is seen to have attacked one plant 

 in a bed, that plant should be immediately taken up and 

 burnt, and the soil round it carefully dressed with lime at 

 the rate of i-lb. to the S(juare foot, a little lime should also be 

 sprinkled round the roots of neighbouring plants. If any of 

 these last show signs of disease, they should be at once 

 removed and burnt, and the soil again treated with lime. 

 When a bed becomes thoroughly infected with a root 

 fungus, the safest method of getting rid of the latter is to 

 remove and burn all the plants in the bed, dress the whole 

 bed with lime at the rate of i-lb. to the square foot, and 

 allow it to remain empty for about two months before 

 replanting. Even then, it is advisable to put into the bed 

 plants different from those which were growing there before. 



If a group of plants in a hedge is seen to have died 

 from the effects of a root trouble, all the plants should be 

 taken up and burnt, and the whole spot surrounded with 

 a trench about IS inches deep and 2 feet wide. This 

 trench should include one or two healthy plants at either 

 end of the diseased patch. The soil from the trench should 

 be thrown into the diseased area. This area should then be 

 treated with lime as above, and, after six months, fresh 

 plants might be planted. 



LEAF AND GREEN STEM DISEASES. ThcSe parts of 



plants are often affected with spots of various kinds, rusts, 

 and mildew, all of which are _due to different fungi. 

 Examples of these are: Canna leaf rust, due to a fungus, 

 Uredo cannae, which appears s.B small orange-coloured 

 spots on the leaves; leaf disease of palms, due to Graphiola 

 phoenifii, which forms small, black,; cylindrical, reproductive 

 bodies on both sides of the leaves;, rose and grape-vine mil- 

 dews, which give the leaves and tips of the branches a silvery 

 white appearance, due to the presence of a white fungus 

 mycelium, which eventually kills the attacked portions, and 

 which may do very considerable damage. 



In the case of rusts and leaf spots, and the palm-leaf 

 disease, the plants may be sprayed with a solution of potas- 

 sium sulphide (liver of sulphur), made by dissolving -i-fc. of 

 this substance in a quart of hot water, and then making the 

 volume up with water to 2i gallons! If preferred, a solution 

 of potassium permanganate, or Condy's fluid, may be used 

 as a spray; the solution .should be of a light rose colour. 

 Before applying the spray, it would be advisable to remove 

 all badly diseased or dying leaves, and to collect all fallen 

 leaves and burn them. 



In the case of mildews, the diseased parts should be cut 

 off and burnt, and all fallen leaves swept up with care and 

 destroyed. The healthy parts of the plants should then be 

 carefully dusted with a mixture of lime and flowers of 

 sulphur. To make this, two parts by volume of flowers of 

 sulphur should be mixed with one part of fine, air-slaked 

 lime. The mixture may be applied by shaking it through 

 a coarse muslin bag. It is advisable to do this when the 

 plants are a little wet. 



Seedlings that are being grown m boxes are often affected 

 with a disease known as ' damping off', especially if the soil 

 in the box is kept a little too moist. This is due to a fungus 

 which spreads along the surface of the soil and attacks the 

 seedlings at the level of the ground, causing them to wilt, 

 fall over, and finally dry up. To prevent this, the dead 

 seedlings should be taken out, and the remainder sprayed 

 with a solution of liver of sulphur, made in the manner 

 described above. 



DISEASES OF WOODY STEMS. Many different forms of 

 fungi can attack the bark and wood of plants, forming 

 cankered areas, splits in the bark, hardened, darkened 

 patches in the bark, or decay of the wood. Their fructifica- 

 tions may be of almost any shape and colour: black, red,yeilow 

 and brown are the commonest. Often, they look like black 

 crusts or are very minute and require a hand lens before they 

 can be clearly made out. But though the fructifications are 

 often small and inconspicuous, the effects of the disease upon 

 the host plant are, unfortunately, usually only too obvious. 

 The only means of preventing the spread of this form of 

 disease is by removing the diseased portions with a sharp 

 knife, taking care to excise at the same time some of the 

 apparently healthy tissue surrounding them, and afterwards 

 to cover the wounds with tar. 



In this short sketch, no attempt has been made 

 to deal with two other important sources of disease, 

 name)}' insects and physiological causes, such as 

 unsuitable soil, or climate, too much or too little 

 sunshine, and the like. Kven the causes actually dealt 

 Avith have been treated very shortly, but it is hoped 

 that enough has been said to attbrd assistance to those 

 interested in the methods of dealing with the fungoid 

 diseases of garden plants. 



