u 



THE AGRICULTURAL NEWS. 



Januaev 13, 191 1 



PLANT DISEASES. 



SUMMARY OF NOTES ON FUNGI AND 

 PLANT DISEASES. 



The following is a classified summar)- of the information 

 given in this Journal under the headings Fungus Notes acd 

 Plant Diseases during the year 1916. 



SUGAI:-CA>E. The occurrence of a disease apparently 

 identical with the wilt disease of India, caused by the fungus 

 Crp/ialofporiu7.i sacchari, is recorded (pp. 1 4, 46) for 

 Uarbados and Nevis. Another Indian disease, due to 

 Cytospora sacchari, affecting leaf sheaths and young shoots 

 has appeared in Porto Pico (p. 270). 



CITRUS TREES. Further information as to citrus canker, 

 the result of experience and experiment in Florida, is 

 summarized on page 142. The view is confirmed that the 

 disease is caused by the bacterium Pseudomonas citri, and 

 evidence is given which shows the organism to be capable of 

 retaining its vitality for considerable periods spent in the 

 soil or in a dry condition on exposed surfaces. A careful 

 search for citrus canker in Porto Rico (p. 271') has led to the 

 conclusion that the island is so far free from infection. 



The liability of citrus trees to forms of die-back appar- 

 ently connected with irregularities of growth, conditioned by 

 climate and food supply, is discussed on pages 366-7 on the 

 basis of a Queensland report describing troubles of this 

 nature closely parallel to those experienced in some parts of 

 the \\'est Indies. 



A type of dry sunken spot on the rind of oranges, which 

 Lad received some attention in Dominica, has now been 

 shown by experiments in California to be due to the es- 

 cape of essential oil on to the surface of the fruit (p.62). 



Affections of lime seedlings, comprising the common 

 'damping-off' disease, and a disease due to a fungus of the 

 'downy mildew' type, are the subject of notes on page 4 1 4. 



COTTON. An article affording further information on the 

 internal disease of cotton bolls appeared on pages 1 26-7. It 

 supplies further evidence as to the dependence of the disease 

 on the pricking of the boll by the cotton stainer or the 

 green bug. A discussion of this subject at the Cotton 

 Conference held in St. Kitis is reported on pages 1^2-3. 



OTHER ( Roi's. The obscure disease of pine-apples known 

 generally as wilt, has given some trouble in Montserrat during 

 the year, and is the subject of an article on pages 174 -J. 

 A summary is given (p. 94) of observations made in Trinidad 

 on the anthracnose of the mango, which is responsible for con- 

 siderable loss of fruit when the weather conditions favour the 

 spread of the cau.sative fungus. On page 31 1> information is 

 ijiven concerning the mode of attack of Untn/ina .onata on 

 Hevea sIlius. A disease of alfalfa in Montserrat is noted f>n 

 page 414. 



tUN"Gicir>Es. In continuation of an article in the pre- 

 vious volume on Burgundy mixture, the results of trials of 

 adhesives and preservatives are reported (p. 30). The addition 

 of milk or resin soap gives such a great advantage in resjiect 

 of adhesion that one or the other should be generally used. 

 The preparation and use of sodium arsenite for the purpose 

 of killing weeds and trees are described on page 2.54. A note 

 on the effect of sulphur on crops appeirs on pige 7;^. 



entomo<;esoiis iunci. The year his been an interest- 

 ing one in respect of the number ot inseot-destroying fungi 

 recorded, new to .science or new to the host or locality. 

 Those which have been ob.scrved in St. Vincent include 

 CvrdiiCtf-!' 'fieltiild. Wakefield, on Cri/i torlopickv!' corli'oihs 

 iioilng i" CoiUuciDu (p. 110), an Ixaria on a grub of either 



Diapiepes or Exophthalmns (p. 110), Spoiotnchum alolu- 

 lijentiii on the cacao thrips (pp. 1 1 0, 430), and several fungi on 

 scale insects (p. 1 10). It may be recorded here that St. Vincent 

 has also yielded an Jsaria on the mole cricket, collected by 

 Mr. S. C. Harland. From Montserrat several collections 

 have been received of an undescribed Empn^a which lives as^ 

 an internal parasite of the green scale. Coccus riridis. ] and 

 seems to kill off large numbers of the insect. 



C'.AUAO. Cacao die-back, connected with lack of 'shade 

 and lightness of soil, is discussed in a report on a visit to 

 St. Vincent printed on pages 206-7 and 222-3. 



\y. N. 



IMPROVEMENT OF INDIAN CORN 

 IN ST. VINCENT. 



The following account of the work in connexion with the- 

 improvement of Indian corn in St. A'incent is taken from the 

 Annual Report of the Agricultural Department for 191.5-16: — 



During the past season experiments have been carried 

 out with the object of improving the native types of corn. 

 The latter are very numerous and differ in respect of every 

 measurable character: in fact no two plants are alike. In 

 general the grains may be yellow, white, red, or brown Iq 

 colour. There is sub division again into Dent and Flint types, 

 and a further separation can be made according to the size 

 and shape of the grain. 



In respect of maturity they are early, being usually 

 ready to reap in ninety to 100 days. In height, they are from 

 3 to 5 feet, and this is a desirable quality, since taller varieties 

 suffer greatly from strong winds. 



The maximum amount of grain per ear when grown 

 under good cultivation, appears to be not more than 7 oz., 

 which seems very small when compared with results obtained' 

 from other countries. After four jienerations of selection no 

 increase whatever has been obtained in the maximum amount 

 of grain per ear, although much uniformity has been obtained 

 in other respects. It is therefore fairly safe to assume thit 

 the native breeds are by nature small, and it is not possible to 

 form combinations of gametes leading to the production of the 

 enormous ears recorded from other localities. 



In this connexion the remark.s of Burft-J )avy are of 

 interest: — 



, 'Poorly bred .seed, moreover, is apt to produce barren 

 stalks and small ears yielding perhaps only 3 oz. of grain 

 apiece. A plant that does not produce S oz. of grain i.s not 

 giving an adequate return for the time and care bestowed 

 upon it, nor for the space that it occupies. In view of the 

 fact that t< .oz. of grain per ear is a common return, and that 

 ears yielding 1-5 oz. of grain are not unkno^vn, an average of 

 3A oz. is absurdly low, and suggests great possibilities for 

 improvement.' 



At present the average yield per stalk in St. A'incent is 

 certainly below 3i oz., and a heavier yielding type is much 

 needed. 



CORN UlRKoVE.MENT. 



The work of com improvement is developing along the 

 following lines: — 



(/) The jtroduction of n uniform yelloiv corn. 



The first crop from ears selected from various parts of 

 the island contained only 55 per cent, of yellow ears the 

 rest being various shades of red. Three generations of 'ma.ss 

 selection reduced the number of red ears to less than 5 per 

 cent The red colour is found in the pericarp, and it is conse- 

 quently a plant character. Ears which are outwardly yellow 

 may be heterozygous, and segregation takes place intoVeds and 



