May, 1909.] 



443 



Horticulture, 



As soon as the temporary supply is 

 exhausted, the plant not only returns to 

 its former state of suffering, but is left 

 more susceptible to injury than before. 

 If the watering is repeated, the emission 

 of rootlets near the surface is encour- 

 aged, and these grow merely to perish 

 again unless the water is continued. 

 Another injury may occur, as already 

 indicated, through the decrease of tem- 

 perature caused by the rapid evapor- 

 ation. 



In very hot weather, during periods 

 of drought, vegetation is greatly sus- 

 tained by the moisture which is return- 

 ed to the earth in the form of dews ; 

 and, in order that these may be most 

 beneficial, the soil should be deeply 

 stirred and continue in a mellow con- 

 dition upon the surface, When the soil 

 is puddled and compacted around a plant 

 by local watering, the amount of dew 

 will be less owing to the decrease in the 

 number of points of radiation presented 

 by the compact ball of soil ; besides, 

 the diminished quantity is evaporated 

 from the impenetrable crust without 

 being able to reach the roots. If 

 watered, the earth should, therefore, 

 be stirred subsequently, or the watered 

 surface be covered with fresh, loose 

 soil. 



If practised at all, the watering should 

 in hot weather be applied to the roots 

 and to the foliage. Evening is the proper 

 time of day, unless in the exceptional 

 case of watering cold frames when frost 

 is apprehended. It is then advisable to 

 water in the morning. The water 

 should not be much colder than the 

 surrounding atmosphere. 



When there are facilities for moisten- 

 ing the whole mass of soil by irriga- 

 tion, that should not be neglected, for 

 its great benefits are undoubted. But 

 even then, unless the surface be so 

 densely covered with the growing crop 

 as to prevent it from being baked by 

 the sun, it would be best to allow the 

 moisture to reach the roots through 

 percolation from open channels or 

 drain pipes near enough to each other 

 and kept full than to cover the soil with 

 water. 



A crop supplied with a sufficiency 

 of soluble manure will suffer less 

 during drought than one inadequately 

 fertilized, and the latter will require an 

 abundance of water. 



Mulching the soil prevents a too rapid 

 evaporation, and is therefore to be re- 

 commended with or without watering.— 

 Gardeners' Chornicle, Vol. XLIV., 

 December 19, 1908. 



PLANT SANITATION. 



ENTOMOLOGICAL NOTES. 



By E. Ernest Green, f.g.s., f.l.s., 

 Government Entomologist, 



On the Introduction of a Predaceous 

 Beetle (Clerus Formicarius) to 



Combat the ' Shot-Hole Borer.' 



Since my return to Ceylon, I have 

 received numerous enquiries on the 

 above subject, accompanied by applica- 

 tions for supplies of this possible enemy 

 of our principal Tea pest. 



I left England too early in the year to 

 enable me to bring out any of the insects. 

 Clerus formicarius makes its appearance, 

 in Europe, during the summer months. 

 I have, however, made arrangements 

 for the collection and despatch of living 

 specimens as soon as they become 

 sufficiently common. I do not expect 

 the first consignment before June or 

 July. 



To prevent possible disappointment, I 

 wish to take this opportunity of making 



it quite clear that the proposed in- 

 troduction is purely of an experimental 

 nature. When the insects first arrive, 

 it may be advisable to keep them under 

 observation, in captivity, for a time, 

 before any distribution can be made. 



I would warn expectant recipients not 

 to be too sanguine of beneficial results. 

 In the first place, the insect is a native 

 of temperate climates, and it is by no 

 means certain that it will adapt itself to 

 a life in the tropics. Secondly, it is 

 more particularly associated with pine 

 trees, though it has been known to 

 occur in oaks and some other species of 

 trees. Moreover, its usual food consists 

 of the larvae of boring beetles that breed 

 in dead and decaying wood. These con- 

 ditions are all very different to those 

 it will find on our tea plantations. 

 Under the most favourable conditions no 

 marked results can be expected for a 

 considerable time. Even supposing that 

 the introduced insect is able to obtain a 

 footing in Ceylon, the increase at first 

 would be slow. There are many other 



