772 Insect and Fungus Pests during Winter. [Nov., 



INSECT AND FUNGUS PESTS 

 DURING THE WINTER: 



THE IMPORTANCE OF PLANT HYGIENE. 



Geo. C. Gough, A.R.C.Sc, 

 Horticultural Inspector, Ministry of Agriculture and Fisheries. 



With very few exceptions, such as the winter moths, one 

 species or another of which is in evidence about this time 

 in the adult moth stage, pests are in a dormant or semi- 

 dormant condition during the winter months. Many of 

 these pests are to be found among the refuse of the 

 crops, and it is therefore essential that the grower should 

 be hygienic in his methods. Plant hygiene or sanitation ig 

 increasingly necessary in these days of high cost of labour, 

 and growers are recognising that it is in the end more economical 

 to spend money on improving hygienic methods and so kill a 

 smaller number of parasites while in a dormant condition than 

 to delay action in the hope that the pests may be effectively 

 removed later. 



Fungus Pests. — A large number of the pests are associated 

 with the soil, and, more especially the fungus spores, are 

 extremely difficult to kill. In the case of some, such as those 

 causing Wart Disease of potatoes, no practical method of killing 

 by treatment of the soil has' been discovered. Another potato 

 disease, Corky Scab, is also perpetuated by infected soil, and no 

 varieties of potatoes are known to be immune from the disease. 

 In the latter case, however, there is good reason to believe that 

 the disease is due largely to wet soils and that drainage may be a 

 remedy, while it is possible that investigations may reveal a 

 chemical which will prove an effective fungicide. Another very 

 common soil pest is Club Boot (or Finger-and-Toe) of turnips and 

 cabbages. On many soils this disease may be kept in check 

 by liming, as the fungus propagates itself best on acid soils. In 

 most instances a heavy dressing of lime is needed, even up to 

 4 tons per acre. Curiously enough, the fungus causing Corky 

 Scab requires the opposite conditions, the disease being more 

 evident in limy soils. 



Insect Pests. — Animal pests in the soil are most effectively 

 controlled by working the land frequently so as to give the birds 

 every opportunity of discovering the insects. It has been noted 

 that grease bands on trees on arable land have caught fewer 

 moths than those on trees growing in grass. 



