146 



THE GARDEN MAGAZINE 



December, 1918 



DESCRIPTION OF TROUBLE 



NAME 



CAUSE OF TROUBLE 



REMEDY 

 REFERENCE 



PINK (Diseases) (See also Carnation diseases) 









Raised blisters of spore-dots in concentric circles on leaves 



Rust 



Puccinia arenariae 



25 



(Insects) (All Carnation insects; greenhouse, white fly and 









two-spotted mite in greenhouse) 









PEONY (Diseases) 









Leaves showing irregular brown blotches 



Scab 



Cladosporium paeoniae 



7 or 8 



Brown or grayish spots on stems, leaves and buds followed by the 



Mold or Botryis dis- 



Botrytis paeoniae 



26, 24, 5 



appearance of a grayish mold under moist conditions 



ease 







PHLOX (Diseases) 









Brown spots on foliage 



Leaf spot 



Septoria divaricata 



7 or 8 



White powdery coating on the leaves 



Powdery mildew 



Erysiphe cichoracearum 



10 (Liquid 

 or dust) 



(Insects) 









Holes in leaves 



Flea beetle 



See Garden Plants 



5 



PRIMROSE (Diseases) (See also gray mold under lettuce diseases) 









Well-defined, oval or circular, brown leaf spots bearing minute dark 



Leaf spot 



Phyllosticata primulicola, As- ) 





spore-fruits 





cochyta primulae > 



7, if severe 



Leaf blotches yellow, centres ashy white 



Leaf spot 



Ramularia primulae ) 





Dark spore-fruits present in extended dead areas of leaf tissue; 



Anthracnose 



Colletotrichum primulae 



ditto and as 



definite spot rather rare 







26 also 



(Insects) (See Fuller's rose beetle) 









SNAPDRAGON (Diseases) 









Spots on stem and leaves, dirty white with brown border; later 



Anthracnose 



Colletotrichum antir; hint 



42, 23, 24, 



black spore-fruits in the centre; leaves blighted or stems girdled 







33 34, 5, 



Tips of shoots wilt and die 



Blight 



Phoma sp. 



5 



Brown, powdery spore-dots on leaves, stems and even seed pods; 



Rust 



Puccinia antirrhini 



25 (infected 



causes death and shriveling of leaves 







plants); 

 30, 5. 8 



(value 

 uncertain) 



(Insects) (green peach aphis) 









SUN FLOWER (Diseases) 









Brown or nearly black spore-dots on leaves which may curl, or die 



Rust 



Puccinia helianthi 



24 (All in- 



and fall 







f e c t e d 

 refuse) 



White powdery coating on leaves and stems 



Powdery mildew 



Erysiphe cichoracearum 



10 



(Insects) (Common garden insects; corn ear-worm; Harle- 









quin cabbage bug; blue sharpshooter of hollyhock; onion thrips; 









oblique-banded leaf-roller of apple insects; potato flea-beetle; 









and two-spotted mite of greenhouse) 









SWEET PEA (Diseases) (See also powdery mildew under pea dis- 









eases; Rhizoctonia disease under beans, potatoes, and other garden 









crops) 









Diseases affecting the aerial parts: 









Seedlings damp off, or older plants show white mold around col- 



Wilt 



Sclerotinia libertiana 



3 



lar and become yellow with later wilting and death; black seed- 









like bodies in or on the affected stems 









Leaves, stems, flowers or pods wilt or turn brown; minute fung- 



Anthracnose 



Glomelella cingulata 



1 (5% for 



ous pustules abundant; disease progresses from young tips 







5-6o min.) 



downward 







(Concen- 

 t r a t e d 

 sulphuric 

 acid for 

 5-ISmin.) 



Leaves dotted or mottled with yellow and frequently curled 



Mosaic 



Non-parasitic 



Control, 

 aphids 



Stems show light reddish-brown to dark brown spots or streaks 



Streak 



Bacillus lathyri 



3 



originating near ground but spreading to involve all other parts 









Flower buds turn yellow and drop off 



Bud drop 



Non-parasitic, Excess of nitro- 



31 (In ex- 







genous fertilizer 



cess) 



Diseases affecting the roots: 









Plants dwarfed and yellow; root system short, stubby and 



Root-rot 



Thielavia basicola 



3 



charred in appearance 









Roots rotting without above symptoms. Several types not sep- 



Root-rot 



Fusarium lathyri, Chaetomium 



3 



arated except by microscopic characters 





spirochaele 





(Insects) 









Spots straw-colored or white with minute black spore-fruits 



Leaf spot 



Phyllosticta violae "\ 





Spots straw-colored or white, centres darkened by mold 



Leaf spot 



Cerospora violae J 





Spots reddish (one sixteenth — one eighth inch) with more or less 



Anthracnose 



Marsonia violae f 





yellowing or intervening portions 





\. 



5, 7, 8, if 



Diseases produce indefinite spots or extended discolored or dead 





f 



severe 



areas on the leaves: 









Advancing from the edge and blighting the whole leaf 



Anthracnose 



Gloeosporium violae I 





Yellow patches on the upper surface becoming powdery below 



Downy mildew 



Pernospora violae J 





TRUMPER CREEPER (Diseases) 









Leaf spots first purplish, later with grayish centre bearing minute 



Leaf spot 



Septoria tecomae 



5 



fungous fruits 









Diffuse, indefinite, brown or obvaceous coating on the lower sur- 



Leaf mold 



Cercospora sordida 



5 



faces of the leaves 









(Insects) (See citrus white fly and general gaiden insects) 









VERBENA (Disease) 









Leaves covered with powdery coating 



Powdery mildew 



Erysiphe cichoracearum 



9, 10 



(Insects) (thrips, leaf-roller and two-spotted mite of greenhouse) 









VIOLET (Diseases) ( Also Rhizoctinia disease under Carnation) 









Roots with grayish-black spots, not penetrating deep; the end of 



Thielavia root-rot 



Thielavia basicola 



If infected 



tap-root of seedlings destroyed or deformed 







soil can- 

 not b e 

 avoided, 

 28, 24, 2 



Diseases producing more or less circular, definite bordered spots: 









Spots generally yellow with brown mold 



Spot disease 



Alternaria violae 



23, 24, 25, 

 26 



(Insects) (especially two-spotted greenhouse mite) 







VIRGINIA CREEPER (Diseases) (black-rot and powdery mildew of 









grape) 









(Insects) (See eight-spotted foresters, hawk moths, and leaf- 









hoppers under grape insects) 









in many leaf-spot diseases and in other troubles infesting the foliage 

 of fruit tif-cs 01 plants. 



24. DESTRUCTION of Dead DfeBRls in gf-n< r;il — dead stems, 

 leaves or fruits. In such troubles as white rust of oyster plant or 

 downy mildew of the onion, the over-winter spores are set free by 

 the .breaking down of plant parts remaining on or in the ground. 

 In the potafo, the stalk-borer winters in the old, dead stems. Es- 

 pr t ially in triK k gardens the general practise of cleaning up and burn- 

 ing all plant debris is a good one, and will lessen the damage from 

 insects, pests, or fungous diseases, 



25. Removal and Destruction of Whom- Plants. In some 

 cases, especially of perennial crops, this is the only thing to do. 

 The tree or plant may be hopelessly infested with an insect pest, 

 or the fungous parasite may be both internal and perennial. This is 

 illustrated in trees badly infested with shot-hole borer or by black- 



benies or raspberries affected with orange rust. The fire blight, a 

 bacterial trouble, may be so severe as to call for equally drastic 

 measures. 



26. Rf.moval and Destruction of Diseased (localized) 

 Parts. This should be done when the trouble is localized. Less 

 severe types of fiie blight infesting the twigs only may be treated in 

 this manner, or the infested canes of small fruits like blackberry or 

 raspberry, or the small branches of trees harboring borers or insect 

 eggs may be pruned out and destroyed. 



27. Burning of Grass or Stubble, not a practise to be 

 generally recommended, but it may be employed in special cases. 

 Ergot-infested meadows may be so treated, while the depredations 

 of the chinch bugs, army worms locusts, and wheat joint-worms 

 may be lessened in a similar manner. 



28. Avoidance of Infected Soil. Fields or gardens may be- 



come infected with soil fungi or insect pests that spend a part of 

 their life buried in the ground or beneath soil debris. A number of 

 the important troubles which may originate from infected soils 

 are the Rhizoctinia disease of potatoes and other crops; the wilt 

 diseases cf cotton, potato, etc.; wire worms, root maggots, etc. 



}. Planting and Cultural Practices 



;29. Plowing. Deep plowing may be used to good ad- 

 vantage against some of the common, injurious insects which spend 

 the winter on or in the soil or surface plant debris in either the egg,, 

 larva, pupa or adult stage. The life history of the pest must be 

 understood in order to take proper advantage of this method. Grass- 

 hoppers' eggs which are laid on grass and stubble, if turned under to 

 a depth of 5 or 6 inches, may hatch, but the young will be smothered 

 without ever reaching the surface. Even adult insects may be bur- 

 ied and smothered. Insects which normally hibernate (spend the 

 winter) below the surface may be exposed and devoured by birds 

 or succumb to unfavorable weather conditions before establishing 

 themselves in new winter quarters. This is why fall plowing is of 

 value in the control of corn-stalk borer, wire worms, sugar-cane 

 borer, corn-ear worm, cut worms, root maggots, etc. 



30. Crop Rotation. One of the principal reasons for disease 

 is the existence of many fungi or insects in the soil, which increase in 

 numbers or amount with the continuous growth of the same crop. 

 Single cropping may thus increase the seventy of a soil infection 

 until the production of a paying crop is absolutely impossible. (See 

 28). This is true in the case of wilt diseases, potato scab, the 

 rhizoctonia diseases, weevils of peas and beans. 



31. Avoidance of Certain Fertilizers which promote the 

 severity of fungous or bacterial troubles, (a) Addition of lime in- 

 creases severity of potato scab, (b) Barnyard manure also increases 

 the severity of potato scab. (c) Nitrogenous fertilizers promote 

 vigorous succulent tissue and so increase danger of pear fire blight. 



32. Use of Certain Fertilizers. The application of lime to 

 a rhizoctonia infected soil is of value since it produces an alkaline 

 condition unfavorable to the fungus. Alfalfa failures may be due 

 to acid soils which may be corrected by liming. 



Control of Water Supply 



33. Reduce the Water Used in Irrigation either by less fre- 

 quent irrigations or by watering for shorter periods. Like the use 

 or strong drink the use of irrigation water is intoxication, for the 

 grower is stimulated by the response which plants make to plenty of 

 water to use a little more. The result is that over-irrigation and 

 over-growth are not uncommon. This is just the condition which 

 favors a bacterial disease like fire-blight of apple and pear, increases 

 the severity of powdery mildew of apple or wheat and aggravates 

 such non-parasitic troubles as bitter rot of apple and winter injury 

 of fruit trees in its various forms. An excess of moisture seems to be 

 favorable for the increase of soil-infesting nematodes, and green- 

 houses that are kept especially damp are frequently overrun with 

 sow bugs. 



34. Water the Soil, not the Plants. In greenhouse crops 

 spraying with a garden hose is a means of spreading certain fungous 

 diseases. If rust appears in carnation beds, the successful grower 

 keeps it in check by wateiing with an open hose between rows. A 

 disease like the late blight of celery may be spread and increases in 

 severity by running the irrigation water down the rows, rather 

 than between them. 



Selection of Site 



35. Avoid heavy poorly aerated soils which are especially favor- 

 able to certain bacterial diseases like black rot of cabbage and black- 

 leg of potato and which predispose stone fruits to physiological 

 gummosis. 



Harvesting and Storage Practices 



36. Early Cutting is designed to interrupt the completion of 

 the life cycle or, wherever possible, to prevent the development of the 

 winteiing stage of the parasite. Two notable illustrations among: 

 fungous diseases are leaf spot and downy mildew of alfalfa; the clover- 

 seed midge may be partially controlled in a similar manner. 



Special Devices 



37. Use of Poisoned Bait, (a) Poisoned bran. Wet 40 

 pounds of bran until the water can be squeezed out in the hand, 

 then stir in 2 gallons of molasses and 5 pounds of white arsenic. 

 Scatter in small piles in the pathway of the pests, (b) Citric bran 

 mask. (1) Mix dry 50 pounds, wheat bran; %\ pounds, white ar- 

 senic or Paris gieen; (2) Mix thoroughly \ dozen Lemons, including 

 rind, chopped fine, 4 quarts, Syrup of molasses; 5 gallons, Wat^r. 

 For use, mix 1 and 2 just before using and add sufficient water to 

 make a wet mash, (c) Slices of cairot, raw potatoes or other vege- 

 tables may be rolled in Paris green and placed in the haunts of the 

 pest. 



38. Borers may be killed by diggingthem out or by inserting a 

 flexible wire into their burrows. Hand-picking of beetles and throwing 

 them into a pan of kerosene is sure but tedious. 



39. The Use of Berries ofsomesoitto prevent the advance 

 or migration of insects, or occasionally of fungi is often effective. 

 (a) Banding with some sticky material, (b) Furrows or trenches. 

 Plowed furrows may be used to check the march of army worm, the 

 retarded army being killed by spraying with strong contact insecti- 

 cide. 



40. Paint sulphur and oil on steam pipes. 



41. Mechanical Destruction of Parasites. Because of 

 their large size and characteristic work, the larvae of tn& 

 sphinx or hawk moths may be easily located, and gathered and 

 destroyed or cut in two with a pair of scissors, wherever found. 

 The egg masses of tussock moths, potato beetles, brown tail moths 

 and others which are generally conspicuous, may also be located 

 and destroyed. Brown tail and gypsy moth egg masses are effec- 

 tually destroyed if painted with creosote 



Seed Selection and Disease Resistant Varieties 



42. The Use of Disease-free Seed or Stock. Certain 

 of the seed-borne troubles can not be readily controlled by seed 

 treatment; against these the selection of healthy seed or seed free 

 from the germs of disease offers an avenue of escape. It is also 

 equally impoitant that all stock used for propagation such as cut- 

 tings, scions, bulbs, etc., be free from diseases or pests. 



43. The Selection of Resistant Varieties of Species. 

 The experience of growers and the results of experimental tests show 

 that it is frequently possible to list varieties into resistant, suscept- 

 ible, and very susceptible groups, and such lists have been published 

 by experiment stations in connection with many of our important 

 crops. A few cf many possible examples may be cited: Durum 

 varieties of wheat and the Kanred show a marked resistance to stem 

 rust; Palmetto asparagus, a variety resistant to rust, has largely 

 replaced the susceptible Conover's Colossal; English varieties of 

 gooseberry are much moie susceptible to mildew than the Ameri- 

 can; the Chinese and Japanese chestnuts aie much more resistant to 

 the bark diseases than the native American Chestnut. 



