i8o Commercial Gardening 



Fungoid Diseases of Tomatoes. There are several diseases of the 

 Tomato caused by various fungi, the most dangerous being: (1) Leaf Spot, 

 (2) Black Stripe, (3) Sleepy Disease, and (4) the Black Blotch or bacterial 

 disease of the fruit. 



The Leaf Spot or Yellow Spot is caused by a fungus known as 

 Cladosporium fulvum. It forms brown mildew -like patches on the 

 under surface of the leaves, and as the mycelium absorbs and destroys 

 the interior tissues the upper surface is spotted with yellow owing to 

 the destruction of the green colouring matter (chlorophyll) in the cells. 



This disease is generally caused by a hot, moist, and stuffy atmosphere. 

 Care should therefore be taken to maintain a proper and equable tempera- 

 ture, and regulate the ventilation without causing cold draughts or currents 

 of air through the houses. In damp cheerless weather in spring or autumn 

 the fires should be kept going, and no more water than is absolutely neces- 

 sary should be given to the plants, so that the atmosphere may be kept in 

 a fairly dry condition. Diseased plants are best taken out carefully and 

 burned at once in the furnaces. 



Black Stripe or Black Rot is caused by Macrosporium Tomati, also 

 known as M. Lycopersici and M. Solani. The plants are attacked when 

 in full growth. The stems begin to shrivel and discolour, with blackish 

 stripes, the leaves to look sickly, blotched, and yellow, and then the fruits 

 to turn black at the eye. The disease is probably due to sour or badly 

 aerated soil, and perhaps too much organic manure. A hot and moist 

 atmosphere are also predisposing causes. As preventives the soil should 

 be deeply turned up and well dressed with freshly slaked or even unslaked 

 lime at the rate of 1 Ib. to the square yard, or about 2 tons to the acre, 

 some time before planting. Overwatering should be avoided, and the 

 atmosphere should be kept buoyant by proper regulation of the ventilators 

 in fine weather. 



The Sleepy Disease of Tomatoes is caused by the spores of Fusarium 

 Lycopersici entering the roots of the plants from the soil. Its presence 

 is indicated by the dull or yellowish colour and drooping of the leaves, 

 and later on by a delicate mildew "bloom" on the base of the stems. 

 These soon become patched with dull orange and signs of decay. If cut 

 through near the base a brownish ring just beneath the bark will be 

 noticed. Although the plants may be attacked when quite young, some 

 weeks elapse before the presence of the disease manifests itself in the 

 ways indicated. 



All diseased plants should be taken up and burned immediately. It 

 is useless spraying them with anything, as the disease is within the plants. 

 The soil should be turned over and sweetened and well dressed with fresh 

 lime. Too much organic manure should be avoided; and basic slag would 

 be the safest artificial to apply to the crops generally, either under glass 

 or in the open air. Proper ventilation should always be given, and the 

 soil should never be drenched and sodden with water. It is better to 

 water once a day properly than to make the soil sodden once a week. 



