804 JOUHNAJ. 01' THE Jj^i'-UriMILVT Ol' Ac-iactLTUltK.— OcT. , 1922. 



DEPARTMENTAL ACTIVITIES. 



(NOTK. — The work of the several Divisions and Schools of Agriculture covers a wide 

 range of agricultural industry in the Union, and we give hereunder notes and observations 

 from certain of them treating with matters of special interest coming under their purview 

 month by month. The object of these notes, which are not concerned with general routine 

 work, is to inform the farmer of such matters as are calculated to be of interest and helpful to 

 him at the present time. — Editor.; 



THE DIVISIONS. 



ENTOMOLOGY. 



Citrus Thrips. — For the i)ast deciide or longer this insect has 

 caused considerable injury to both citrus trees in nurseries and fruit 

 on bearing trees in orchards. 



This til rips is a very minute i'our-wino'ed fly, being- so small tliat 

 it usually escapes notice. The insect becomes numerous and most 

 injurious about the time the citrus trees are in bloom. The tender 

 young g'rowth and the setting fruit is gnawed, a curling of the leaves 

 and a wliitencd irregular zone around the stem end of the fruit being 

 the result. On young nursery stock the damage is often serious, and 

 sometimes a very considerable and unsightly scarring of the fruit 

 occurs. This jiest has been observed or reported from practically every 

 citrus-growing centre in the Union. 



As experiments on the control of thiips have hitherto not been 

 carried out in South Africa, no dehnite recommendations can be made, 

 but a review of the results obtained in California and in other places 

 where the pest has done extensive damage may prove interesting and 

 suggestive. In California four applications of lime sulphur at the 

 dosage of one jiart to eighty parts of water are recommended; the 

 first application being made just after most of the jj^tals have fallen; 

 the second ten or hfteen days latei; tlie third three to four weeks 

 after the second; the fourth when the insects are numerous on the 

 foliage. Lime sulphur sometimes causes a slight l;urning, but other- 

 wise is very eft'ective, and cheaper than tobacco extract, which is a 

 spray sometimes used for this pest. For tobacco extract, a dilution 

 of one part in 360 parts of water has given good results in California. 

 Spraying, however, for this pest in California has not proved ])rofitable 

 enough to justify its continuance, except in nurseries. Another 

 method which has been favouiably reported on is dusting with sulphur. 



