78 STATE HORTICULTURAL SOCIETY. 



APPLE SCAB. 



L. R. STANLEY^ TRAVERSE CITY. 



Apple scab is tlie worst disease with Avbicli tlie fruit grower has to 

 contend, in the same way the cochlling moth is the worst insect that he 

 has to fight. 



During seasons that are wet and cold, such as we had this summer, 

 the scab will often cause a loss to the apple growers of the State of 

 25% of the market value. 



Scabby apples are packed and put on the market, because the scab 

 does not entirely destroy the usefulness of the fruit, but a scabby apple 

 in a good barrel of fruit is like a scrub cow in a pure blooded herd of 

 Holsteins. It detracts from tlie appearance of the rest of the barrel, 

 and lowers the price which the producer gets on the market. 



The ajjple scab disease is the enemy of tlie fruit grower for at least 

 five reasons: 



1. It interferes with the normal functioning of the foliage. 



2. It retards the twig and wood growth of the tree. 



3. It makes abnormal apples. 



4. It makes unsightly apples. 



5. It keeps the Michigan apple growers from putting up a first grade 

 pack, and thus getting a first grade price for the pack. 



The cause of this disease is a fungus or a very small plant that lives 

 at the expense of the apple and the apple tree. Its spores or seed get on 

 the young fruit or leaves in the spring, and they begin to grow and 

 send out little roots or mycelium. These burrow down through 

 the skin of the apple or the leaf, and produce more mycelium. These 

 fine roots send up branches to the surface, and on these branches are 

 produced more spores. This causes the skin to rupture and we have 

 the typical scab spot. The rupturing of the skin allows the entrance 

 of other diseases such as pink rot, brown rot, and a number of others. 

 These spots may form at any time throughout the early part of the 

 summer, but usually just after a rain. 



Another stage of the disease is found on the dead leaves in October. 

 This stage matures between early fall and the following April. It is 

 a round sac-like body on the under surface of the leaf, and inside of it 

 are a number of long slender cases, in each one of which are eight 

 spores. At the proper time in the spring, these spores come out and 

 infect the leaves and young fruit. 



The secret of the control of apple scab is in getting the spray on the 

 trees before the spores get there. Concentrated lime-sulphur should be 

 applied before the leaf buds open, and dilute lime-sulphur just before 

 and after the blossoms fall. When properly applied, the spray covers 

 the tree from top to bottom with a thin coating. Now when the spores 

 come along, they settle down on an apple, send out their little roots and 

 try to get a living. But before reaching the apple they must first go 



