28 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ON KEEPING ORCHARDS CLEAN. 



By Professor H. M. Lefroy, M.A., F.Z.S., Entomologist to the 



Society. 



[Read February 2, 1915 ; Mr. E. A. Bun yard, F.L.S., in the Chair.] 



The title of to-day's lecture sums up the most practical advice that 

 can be given to the fruit-grower in this country, and I will try to show 

 why it is of such importance. Keeping orchards clean has a value 

 from more than one point of view, but I have treated it solely from a 

 rather neglected one, that of the entomologist who seeks to prevent 

 the great waste of fruit caused by insect pests in orchards. It has 

 a significance also from the horticultural point of view, and very 

 definitely from the fungus-disease aspect, but it will be sufficient 

 to-day to deal with it as it applies to insect pests. 



Our fruit-trees suffer from a variety of pests which fall into two 

 classes : the constant pests, such as the Woolly Aphis, the Mussel 

 Scale, the Apple-sucker, the Codling Moth, the Pear Midge, and a few 

 others ; and the occasional pests, far more numerous in kind, far less 

 important individually, which occur sporadically and irregularly on 

 fruit trees, which are not always present in abundance and so are 

 not noticed, but which by their total effect cause a serious loss to 

 the crop. 



It is possible to take vigorous direct measures against any one 

 of the first class : if one has Apple-sucker one sprays for it, and if 

 one does not it becomes an increasing pest. It is impossible to take 

 direct measures against each casual pest, since one never knows 

 whether they will occur ; against them one can only adopt general 

 measures, act on broad lines, and use methods devised generally 

 to check any of this class of pest from becoming abundant on our 

 fruit trees. They cannot be checked on their wild food-plants, but 

 something can be done to discourage their activities in orchards. 



You may consider the importance of the latter class of pests is 

 being exaggerated, and think of orchards you know in which there 

 has been no very obvious destruction by insects the year through — the 

 trees have not died, they have not been devastated by caterpillars, 

 there has been the usual amount of fruit — but the damage shows 

 itself clearly and definitely when the fruit ripens. How much of 

 the fruit is perfect ? How much can be put av/ay and kept ? There 

 is usually an enormous percentage of fruit that is damaged, that will 

 not keep, that is just a little flawed ; all this is avoidable if one can 

 check the pests, and it is this kind of damage that these varied insects 

 cause. One should get every apple off the tree perfect, the skin 



