KOOT CROPS. 5 1 ■> 



Phoma Rot. 



A disease due to a species of Phoma has been noted on turnips in this 

 State. (.See remarks concerning allied species causing Blackleg on cabb ■ 

 r e 670]. ) 



There are other fungus diseases of turnips that are common to cabbages 

 and cauliflowers, references to which are made in connection with cauli- 

 flower- and cabbages in the vegetable section of this Handbook. (See Black 

 R ' page 668]; Club Root [page 668]; Downy Mildew [page 670].) 



Turnip Aphis {Aphis rapes, Curtis). 



This is the common turnip aphis, which infests the under surface of the 

 leaves, in the first instance, causing them to become wrinkled and curled up. 



The last brood of the winged summer aphides lays winter eggs, protected 

 with a stout skin, and attached to the plants and rubbish. These eggs 

 produce the first generation of wingless females. These produce larvae 

 which become the second generation of winged males and females. 



It is the first brood from these wingless females that, forming little 

 colonies, spread over the plants, sucking up the sap and aborting the tissue, 

 cause the damage to the plants. These aphides mature and multiply with 

 such marvellous rapidity that, unless some precautions are taken, the plants 

 soon sicken and stop growing, or at least produce poor turnips. 



The males are dull yellow creatures with long slender antennae, delicate 

 glassy wings, and very soft bodies. The females are similar in form, but 

 somewhat larger, and deep green in colour. 



Clean cultivation is the most satisfactory method of control, the eggs 

 deposited by the last brood of the season being destroyed, and the following 

 crop thus saved from attack. Field spraying is expensive, but if it pays to 

 spray the crop, kerosene emulsion or tobacco wash is effective, provided it is 

 used as soon as the first aphides appear. If once the plants become badly 

 infested, it is very hard to keep the aphis down. 



In the case of field crops, the 'promotion of vigorous growth by surface 

 cultivation and manuring will help more than anything else. Fortunately 

 there are an immense number of parasites that live upon and in all kinds 

 of aphis, and they are a great factor in ordinary years in keeping the pests 

 under control. 



Other Insect Pests. 



A small light-brown moth (Godara comalis) will, in its caterpillar stage, 

 attack the foliage of turnips and the horse-radish. Where plentiful enough 

 to seriously affect the turnips, a spray of arsenate of lead (1 lb. in 20 gallons 

 of water) could be used. 



Cabbage Moth (Plutella maculipennis) will occasionally attack turnips, 

 and garden crops could be treated with lime and tobacco dust, in accordance 

 with the. suggestions as to the control of this pest under cauliflowers and 

 cabbages, if the infestation becomes severe. For field crops reliance must 

 again be placed on clean cultivation, and the destruction of rubbish on 

 .neighbouring land, where the moth is likely to deposit eggs. 



Cutworm (page 437), eelworm (page 508). 



