Be Your Own Plant Doctor -By H. H. whetzel, 



Plant Pathologist, 

 Cornell University 



A NEW KIND OF TABLE, DESIGNED TO HELP THE AMATEUR TO RECOGNIZE THE COMMONER 

 DISEASES AFFECTING HIS PLANTS, SO THAT HE MAY APPLY THE PROPER REMEDY PROMPTLY 



[Editors' Note. — The following tables are unique. Nothing of the kind has yet been pul before the gardener in such an easily understood way. Most 

 tables, or "spray calendars," assume an acquaintance with what may be causing the trouble or disease. In the present case the remedy is arrived at by 

 working from the known to the unknown. First of all the plant is given, then the gross apparent character of the trouble, the time of observation, and the general 

 description of the cause; and from these the name of the disease is arrived at. The remaining columns tell of the immediate remedies and general preventive 

 measures. A synopsis of remedies and their modes of preparation follow the tables. A similar table, prepared by Dr. E. P. Fell, and covering the insects, 

 :cas given in The Garden Magazine /or May, 1909, page 221.] 



PRACTICALLY every plant is injured 

 more or less by parasitic fungi, but not 

 in every case is the resulting loss sufficient to 

 warrant the expenditure of time and money 

 for its prevention. For this reason the fol- 

 lowing tables are not absolutely compre- 

 hensive, and it is probable that the grower 

 will notice on his plants lesions of a type 

 not described in them. However, there will 

 be little loss and no cause for alarm in most 

 of these cases. The tables treat of all the 

 important diseases of the plants listed, and 

 the control measures recommended are in 

 every case those which have in actual prac- 

 tice proven most efficient and at the same 

 time least troublesome and expensive. For 

 lack of space in the column labeled "control 

 measures" very little detail could be given, 

 but the full data is given on page 256. 



It is one thing to know what fungicide 

 to use, and another to know just how to 

 make and exactly when and how to apply 

 it. The tables will supply the first. 

 Fungicides, more often than insecticides, 

 are used primarily to prevent injury, rather 

 than to cure that which has already taken 



place. In other words the fungicide serves 

 as a protecting armor to the plant. 



In many cases after the fungus once 

 gains entrance to the host it is too late and 

 absolutely useless to spray. However, 

 in a few cases this is not true. The 

 powdery mildews of roses, hops, lilac, 

 cherry, etc., live for the most part on the 

 outer surface of the leaves and can be 

 entirely destroyed (even after they have 

 attached themselves) by spraying with po- 

 tassium sulphide or dusting with sulphur. 



Not all methods of disease control have 

 to do with spraying. Pruning out of 

 diseased parts, seed treatment, soil sterili- 

 zation, crop rotation, application of various 

 substances to soil, drainage, complete 

 eradication of alternating host plants, 

 destruction of insects carrying disease 

 germs, etc., are some of the other remedies. 



In the above tables no superfluous pre- 

 cautions are suggested and the grower 

 will find it necessary to follow the direc- 

 tions closely if he hopes to get good results. 

 In many cases the delaying of the appli- 

 cation of a spray for a day will render it 



Diseases of Vegetables 



wholly useless. For this reason the imple- 

 ments for spraying should be always in 

 condition for use, and the application of a 

 spray on short notice should be possible. 

 No grower who hopes to obtain clean crops 

 should fail to have in readiness the means 

 for combatting the many fungus foes which 

 are sure to assail his crops. 



The owner of the small garden and most 

 amateurs to whom gardening is merely a 

 relaxation and a side issue, will find it 

 much to their advantage to rely upon the 

 ready prepared articles which are espe- 

 cially manufactured for their needs. 



These proprietary articles are made from 

 definite formulas and although they may be, 

 in some cases, somewhat less efficient, 

 volume per volume, than the freshly pre- 

 pared article, still their convenience and 

 their known efficiency justify their use. 

 In some cases, particularly with some of the 

 tobacco extract preparations and other 

 contact poisons that are used for insects, 

 the ready prepared commercial article 

 will be found distinctly superior to the home- 

 made. 



SYMPTOMS 



CONTROL MEASURES 



Asparagus. . 



Bean 



Bean 



Bean 



Bean 



Beet 



Beet 



Beet 



Cabbage and 

 cauliflower 



Cabbage and 

 cauliflower 



Celery. 



Celery.. . . 

 Cucumber 



Reddish or black pustules on 

 stem and branches 



Circular, brown or purplish spots 

 on pods, stems and leaves. . . . 



Large dead spots on leaves. 



Watery spots on pods 



Rusty spots on leaves 



White moldy growth on pods 

 and at base of stem 



Circular spots on leaves, with 

 gray centre and purple border. 



Base of leaves black, root rotted 

 and cracked at crown 



Warty and scabby spots on 

 roots 



Leaves yellow, then black on 

 margin, later fall off. Heads 

 not formed 



Plants stunted and unhealthy 

 looking, roots much deformed. 



Yellowish spotted leaves, 

 in seed beds 



Often 



Yellowish, spotted leaves. Often 



in storage 



Yellow leaves later drying up. . 



Summer and 

 autumn. . 



Summer. . . . 



Summer. . . . 



Summer and 



autumn. . 



Summer. . .. 



Summer and 

 autumn. . 



Summer and 

 autumn. . 



Summer and 

 autumn. . 



Early part 

 of season 

 up to ma- 

 turity. . . . 



From seed 

 bed to 

 time of 

 maturing . 



Early sum- 

 mer 



Rust. 



sum- 



Late 



mer 



About fruit- 

 ing time 



Anthracnose 



Blight (bac- 

 terial) . . . 

 Rust 



Root and 

 stem-rot. . 



Leaf-spot. . . 



Root-rot . . . 



Scab 



B la ck-ro t 

 (bacterial) 



Club-root. . 



Early blight 



Late-blight . 



Downy mil- 

 dew ("the 

 blight") . . 



Spray with bordeaux 5-5-50, containing a 

 sticker of resin-sal soda soap, once or twice 

 a week all season 



Plant clean seed obtained by sorting for ab- 

 solutely clean pods. Spray with bordeaux 

 5-5-50 



Spray with bordeaux as for anthracnose 



Burn old leaves and vines each year 



Good drainage, liming of soil. In greenhouse 

 sterilization of soil with formation 



Spray early with bordeaux 5-5-50. After- 

 ward every ten days 



Good drainage and liming of soil recommended. 



Practice crop rotation 



Treat seed in mercuric bichloride 1-1000 for 

 15 min 



Plant only healthy plants, use no manure con- 

 taining cabbage refuse. Practice crop ro- 

 tation. Avoid clubbed plants for trans- 

 planting 



Spray with ammoniacal copper carbonate 

 6-3-45, make about eight applications, begin 

 when plants are in seed bed 



Spray as for early blight, but continue to 

 harvesting time 



Spray with bordeaux 5-5-50, every two 

 weeks from time plants begin to run 



Fertilize and cultivate thor- 

 oughly. During cutting season 

 permit no plants to mature 

 along road way, etc. 



Spray when plants first appear, 

 when first pair of leaves are 

 expanded and when pods 

 have set. 



Difficult to control. 



Plant resistant varieties. 



Not of sufficient importance to 

 warrant soil treatment in 

 the field. 



Most important disease of the 

 beet. 



No satisfactory treatment. 



No treatment effective. 



Plant on clean soil, practice 

 crop rotation. 



If necessary to use infected land 

 apply lime 2-5 tons to acre 

 previous fall or earlier. 



Destroy diseased plants and re- 

 fuse. Spray often enough to 

 keep new growth covered. 



Have good drainage. 



Burn diseased plants in fall. 



2-17 



