Vol. VIII. Xo. 191 



THE AGRICDLTUKAL NEWS. 



2S!) 



STUDENTS' CORNER. 



AUGUST. 



Last Period. 



Seasonal Notes. 



In cases where artificial manures are emploj-ed for limes 

 or cacao, notes should be made as to the . kinds that are 

 generally used in this connexion, and tlie reasons, in any 

 siiecial instance, for their employment. Wli^t manurial con- 

 stituent has the greatest importance in the matter of fruit 

 formation ? Lime and other citrus plants should be specially 

 watched after a good fall of rain in order to find out if there 

 is an increase of the fungoid parasites of scale in.sects. At 

 the same time a look out .should "be kept for small hole.s in 

 the covering of scale insects ; in this way, the presence or 

 absence of other insects which are parasitic on them will be 

 indicated. "Where lime trees have been I'ecently pruned, 

 determine whether this has been carried out carelessly or not, 

 and find out if there have been any harmful results from 

 careless pruning or by omission to cover the wounds with tar. 

 By careful examination evidence may be obtained that care- 

 lessness in removing branches has provided places for the 

 entrance of the lime tree borer. Where Bengal beans were 

 used as a cover crop last year, notice if there is any increased 

 growth i;onseqitent on their use : also clo.sely observe the state 

 of trees which have become covered with this plant. A close 

 ■watch must also be kept, throughout the plantation, for the 

 return of injurious insects and the growth of love-vine 

 (dodder). Branches infested with this must be carefully cut 

 out and burnt, as it is not only readily propagated by seed, 

 but also by means of small pieces of the stem. 



When cacao is badly attacked by tlu'ips, the effect of 

 this pest on the leaves and pods, and on the trees themselves, 

 should be noted. Examine the leaves : the surface on the under 

 side, together with part of the interior has been eaten away. 

 The pods also show the effects of the pest chiefly on tlie under 

 side. When they are first attacked, small areas which have 

 a deep brown colour are seen ; these subseijuently grow 

 larger, and the whole pod becomes deep broYf, so that such 

 immature fruits are frequently gathereii as ripe ones. 

 A study should be made of the methods which are adopted 

 to control the pest. Find out, if possible, which of the 

 ■washes that are recommended for the purpose is the best, 

 And what results from the application of lime on soils w'here 

 there is a large proportion of organic matter, present. Infor- 

 mation regarding thrips will be found in the Agricultural 

 H'ews, Vol. V, No. 120 ; in the West Indian Bulletin, 

 Vols. II, pp. 175-90, and IX, p. 190 ; and Bamphlet No. 58, 

 Insects I'ests of Cacao. 



In going through a c(jtton field it will, often be noticed 

 that the plants have failed to grow evenly ; some appear to 

 be making a healthy growth, while others are dwarfed, and 

 may even be showing very evident signs of disease. Attempts 

 should be made to find in each case the reason, or reasons, 

 for this. Among these are, speaking generally, the presence 

 ■of too much moisture, a physical condition of the soil which 

 is unsatisfactory as regards germination, attacks of anlhrac- 

 nose on the sprouting seed, and planting too deeply. What 

 ^re the reasons for the lack of development of the plant from 

 seeds that are planted deeply ; The young cotton plants will 

 Tiow have reached the stage at which they may he tliinned 

 ■out. It will form a good exercise to omit this thinning in 

 the case of a few plants, and to perform the operation roughly 

 in that of others ; then to compare the growth of the plants 

 thus treated with that which has resulted from the careful 



thinning out that the others have normally received. What 

 do you learn about root growth and absorption from this 

 experiment 'i 



In those parts where there has recently been a good 

 supply of rain, attention will be drawn to the svibject of 

 drainage. That on sugar estates forms a specially useful 

 object-lesson. The various distances/ at which drains are 

 made for carrying away surplus water from difierent kind.s 

 of soil, and from fields on the fiat aiid on different slopes 

 should be noted. What special arrangements in draining 

 have to be made (1) where there are small springs, (2) where, 

 during heavy rainfall, the smaller particles of soil are carried 

 away .' Study the connexion between drainage and the 

 position of the water table, with special reference to the 

 growth of roots. 



Questions for Candidates. 



PRELIMIN.^EY (JUE.STIONS. 



(1) A field, in which the soil is in good condition, is left 

 under grass. Does the soil gain in nitrogen content 1 



(2) What is meant by .secondary thickening of stems? 

 Describe the structure of the stem of (a) the hibiscus, (b) the 

 cocoa-nut palm. 



(3) What changes take place when a sample of soil i.s 

 heated strongly ? 



INTEEMEDI.A.TE QtTESTION.S. 



(1) A field of heavy non-calcareous clay, which had been 

 green-dressed with pigeon peas, was found to give a very poor 

 growth of cane. What was the reason for this 'I 



(2) What is meant by the term 'bud variation ' ? Does 

 this ever occur in the sugar-cane l 



(3) What effects has the food of animals upon the 

 resulting manure ? 



EDUCATIONAL AND ECONOMIC VALUE 

 OF PLANT COLLECTIONS. 



By means of a prize-scheme to operate in schools, 

 the Director of Agriculture in Rhodesia is attempting 

 to supplement the usual methods of gaining informa- 

 tion with regard to the possible economic importance 

 of such plants as are not under general cultivation, 

 whether as products of commercial value, or because of 

 the dangerous or objectionable properties which they 

 may possess. 



To this end, prizes to the value of £15 are offered for 

 competition among school children, who will forward collec- 

 tions not exceeding 100 dried specimens. These are ta 

 be accompanied by the following | particulars, as far_ asL 

 possible : English and native name, date of collection, 

 habitat and geographical position, appearance, uses and 

 properties of the part utilized. Adults are invited to assist 

 in the work either by contributing to collections, or by 

 forwarding specimens direct to the Department of Agri- 

 culture, whose property all such material will become. la 

 judging the collections, regard will be had to the skill shown 

 in .'-"election, completeness of the specimens, fidlness of their 

 history, and to the manner of preservation of the specimens. 



It seems that the adoption- of such a scheme in 

 other countries, where wild plants are put to many 

 uses by the natives, would be useful both from ai> 

 economic and an educational point of view. 



