PLANT DISEASES 



313 



Equal parts of the blue vitriol solution and the dilute milk of lime are 

 then mixed together. This mixture is known as 5-5-50 Bordeaux. 

 Other mixtures, as the 4-4-50 and the 3-3-50, are prepared in a similar 

 manner, using proportionately less copper sulfate and hme. 



Sulfur, ground fine enough to pass through a 200-mesh to the 

 square inch screen, may be applied with any good dusting apparatus 

 for the control of a number of diseases of plants. 



The More Common Diseases of Garden Crops 



APPLE 



Bitter rot {Glomerella cingulatn) caiises 

 a rot of the fruit, which at first is brown in 

 color ; later small pink masses appear on 

 its surface. Finally the whole fruit rots and 

 then shrivels into a mummy, which some- 

 times clings to the tree. Cankers also form 

 on the limbs. They should be removed in 

 the Winter and burned. Spray with Bor- 

 deaux mixture (4-4-50) once before buds 

 open and afterwards according to the 

 weather. 



Black rot or New York Apple tree 

 canker (Physalaspora Cydoniae). Fruit is 

 rotted and covered with black pimples and 

 shrinks to a mummy; leaves are often 

 spotted and cankers develop upon the limbs. 

 Remove cankers or cankered limbs. Spray 

 foliage with Bordeaux (4-4-50) about the 

 middle of July and again two weeks later. 



Blister canker (Nummerlana discreta). 

 Cankers are formed on the limbs or body 

 and at first are dull brown in color, later 

 becoming darker. When the canker en- 

 larges the bark blisters and comas off. 

 Finally the small, raised, nailhead fruit 

 bodies of the fungiis are formed on the 

 surface of the wood. Cut out small cankers. 

 If large, remove the diseased limb. 



Broven rot (Sclerotinia cinerea). See 

 Plum. 



Fire blight (Bacillus Amylovorus) . See 

 Pear. 



Powdery mildew (Podosphaera leuco- 

 tricha). The leaves become covered with a 

 white or grayish powdery-like mildew which 

 usually affects their growth where infection 

 is severe. Twigs also are attacked. In the 

 latter part of the season minute black bodies 

 may Be seen on this whitish overgrowth. 

 Spray with a mixture prepared by adding 

 3 pounds of copperas (iron sulfate) to 50 

 gallons of 1-50 lime-sulfur solution. About 

 four sprayings are recommended during 

 the season. 



Rust (Gymnosporangium Juniperi-vir- 

 ginianae). One stage occurs on the red 

 Cedar as Cedar apples which are brown 

 gall-like growths and produce yellow gel- 

 atinous horns in Spring; the other stage 

 occurs on Apple leaves and fruits. The 

 spots on the Apple leaves are at first small 



and yellow, but later they become crange 

 colored on the upper side of the leaf; small 

 pimples develop on the spots while on the 

 lower surface minute cuplike structures are 

 formed, the edges of which are split in a 

 starlike manner. Severe infections cause 

 the entire leaf to turn yellow and fall. To 

 control this disease eradicate the Red 

 Cedars within a radius of at least one mile. 

 Spraying is not very effective, but lime- 

 sulfur 1-40 may be used; spray the new 

 leaves as they unfold. 



Scab (Venturia inaequalis) occurs on the 

 leaves and fruit. It ahows first on the 

 under, later on the upper surface of the 

 leaves as circular, olive green, superficial 

 patches which later turn darker. The leaf 

 under the spot may become convex or 

 puffed. When infection is severe the entire 

 leaf may be involved. On the fruit the spot 

 is at first olive green and later has a dark 

 center with a white papery margin. This 

 is one of the most serious of Apple diseases. 

 Spray with lime-sulfur (1-40). (1) When 

 the buds show green; (2) Just before the 

 blossoms open; (3) When the petals fall; 

 (4) Two or three weeks after the petals fall. 



Sooty blotch or Fly speck (Leptothy- 

 rium pomi). Irregular, superficial, sooty 

 blotches which may be rubbed off the apple 

 skin, or minute fly specks thickly crowded 

 in spots over the surface of the fruit. The 

 treatment for Apple scab will easily control 

 this disease. 



Stippen, known also as "bitter pit." A 

 disease not due to an organism, but is said 

 to be due to the improper distribution of 

 water to the fruit. It may be recognized 

 by the depressions on the surface of the 

 fruit which are caused by the development 

 of brown, corky areas in the flesh of the 

 apple. Good cultural practices, as proper 

 drainage, cultivation and pruning should 

 be followed. Uniformity in the water 

 supply during the growing season reduces 

 losses from this disease to a minimum. 



ASPARAGUS 

 Rust {Puccinia asparagi) attacks the 

 green tops which develop after the shoots 

 have been cut. It may be recognized by 

 the final dying of the tops and the small red 

 or black colored pustules formed on the 



