18 TURNIP. 



years, is sound agricultural practice, based on knowledge of the wants 

 of the Turnip plant, and of the habits of the Turnip Fly. 



The Turnip is very succulent, and needs plenty of food and 

 moisture, and moderate warmth to press on growth ; and the attacks 

 of the Turnip Fly are most serious in heat and drought, for in such 

 weather the "fly" or "flea" beetles propagate more freely, and use 

 their wings, and consequently spread further ; also heat and drought 

 together keep back the growth of the plants, which are therefore 

 exposed for a longer time to fly-ravage. Frost, or cold with drought, 

 or cold with rain, or any kind of weather or circumstances that are 

 unfavourable to plant-growth, also throw the crop under the power of 

 this pest ; but heat and drought are the worst, because they are good 

 for the fly as well as bad for the plant. 



In many of the following notes it will be observed that it is advised, 

 by autumn cultivation (where this is practicable), or by working the 

 land as early in the spring as it can be done, to preserve the moisture 

 that has accumulated during the winter for the benefit of the germi- 

 nating plants. By thus preparing the soil beforehand, little stirring 

 of the ground is needed when the time comes for seed-sowing ; and, 

 instead of the land being repeatedly thrown open to (what is often at 

 so wing -time) a drying sun and air until the surface moisture is com- 

 pletely dried out, the application of the use of cultivators or 

 scarifiers, which expose little fresh soil, is enough. The surface 

 of the ground, which has been mellowed by exposure to frost, or 

 weather influences, gives a fine tilth suitable for germination, retains 

 moisture evenly, and gives it out gradually and genially for plant- 

 growth. The most favourable conditions are thus secured for the 

 germinating crop, and there is the further advantage that where 

 the land has thus been well cleaned and cultivated beforehand there 

 will have been all the less food and shelter for the fly in winter and 

 spring, and consequently less risk of attack. 



What is the reason of the attack of 1881 we do not know with 

 certainty ; but looking at the way in which this pest infests Charlock, 

 and spreads from it even in common seasons, and considering the 

 quantity of this weed that followed on the wet season of 1879, together 

 with the impossibility, after that wet, of giving the land the thorough 

 cleaning needed to keep down the fly ; such conditions point to the 

 attack being fostered during 1880, and breaking out in unusual 

 numbers when favoured by the unusual heat of the early summer of 

 1881, which was just suitable for its increase. The following notes 

 refer mainly to this point : 



