VEGETABLE GROWING IN NEW SOUTH WALES. 103 , 



it, dark spots can be noticed. These often form in clusters, and increase in 

 number and size, until they join up at their margins, and the whole leaf 

 becomes a dirty greenish brown colour, and withers away. The spots may 

 appear on the upper or the lower surfaces of the leaves, and the leaf stalks 

 may also become affected. Inner leaves may be found to resist the disease for a 

 time, but under warm and moist weather it spreads rapidly from the older to 

 the younger leaves, and the whole plant is rendered useless. Small black 

 points, from which spores are produced in moist weather, appear on the brown 

 dead areas. The blight usually appears after rain or heavy fogs, and spreads 

 rapidly with a plentiful supply of moisture. If diseased plants go to seed 

 the fungus also attacks the seed, and passes the winter in it unharmed, 

 giving rise to actively infectious spores in spring. Seedling plants may 

 show the characteristic spots on the leaves at a very early age. The fungus, 

 also passes the winter on diseased foliage and stems. 



Preventive measures should commence with the seed. This should be 

 steeped for three hours in a mixture of formalin 1 part, water 600 parts, 

 frequently well stirred and then taken out and dried. Weak Bordeaux 

 mixture (see page 128) should be applied to the plants in the seed-bed. 



Care should be taken that only healthy plants are transplanted, and the 

 first field spraying should be 'given about four to six weeks afterwards* 

 Thereafter spraying should be given at periods of three or four weeks, but 

 more frequently in wet weather. Until the plants reach a height of about 

 15 inches, spraying may be done, travelling in one direction only, but when 

 above that height the spraying should be done twice, proceeding the second 

 time in the opposite direction to the first time, thus completely covering both 

 sides of the plants. The quantity used by this method is found to be about 

 30 to 40 gallons per acre. Before spraying, go over the rows and remove all 

 dead or badly affected leaves and burn them. Diseased plants or refuse 

 from a previous crop should not be left in the field. 



Where the disease has been serious, rotations should be made, extending: 

 over several years. Recent experiments have shown that varieties vary in 

 their resistance to attack, so that careful observations should be made as to 

 those most resistant under the local conditions, and cultivation confined to 

 the least susceptible varieties. 



Mildews of Beans and Peas. 



Beans and peas are attacked by a number of fungi which produce diseases 

 known as mildews. 



Damping-off Mildew. The conditions which favour the development of 

 this disease are a considerable degree of warmth, abundant moisture, and a 

 crowded condition of the seed-bed. Plants are mostly infected by means of 

 water which is drawn from a source where the fungus is present. This may 

 be overcome by watering from a tank supply. Precautions may be taken 

 against another source of infection, the seed-bed itself, by sterilising the 



