DISEASES OF PLANTS. 253 



Noxious weeds {Rpt. Dept. Agr. NorthweM Territories, 1899, pp. 29-40). — A report 

 is given of the distribution of a number of troublesome weeds and the activity of the 

 inspectors in enforcing the laws on weed destruction. 



On tlie geographical distribution of some of our weeds, J. Holmboe ( Tidsskr. 

 Nor>ike Lditdhr., 7 {1900), No. 4, ]>]>■ lo5-171). 



Experiments in weed prevention, J. A. Voelcker {Jour. Roy. Agr. Soc. Eng- 

 land, 3. ser., 11 {1900), No. 41, PP- 110-115, fig. 1). — In this pot experiment, 4 series 

 were used: 1, control; 2, sprayed with ammonia liquor from gas works; 3, treated 

 with salt at the rate of 5 cwt. per acre and subsequently sprayed with a 2 per cent 

 solution of sulphate of copper; 4, sprayed with carbolic acid solution. The weeds 

 that appeared were speedwell, groundsel, shei^herd's ^urse, goose foot, and knot 

 grass {Polygonum aviculare). Cias liquor used in its full strength, containing 2.93 per 

 cent ammonia, killed all the weeds except goose foot and knot grass. The other 

 chemicals used were found to be practically useless for weed prevention. 



Spraying for weed destruction {Deal. Landw. Presse,27 {1900), No. 53, p. 679). — 

 Notes are given on the successful spraying with solutions of iron sulphate for the 

 destruction of field mustard in a number of crops. 



Bur medic {Queensland Agr. Jour., 6 {1900) , No. 3, p. 209, pi. 1). — Notes are given 

 on Medicago denticulata which is considered a very troublesome and injurious weed 

 in pastu^-es. 



Destruction of charlock {Jour. Bd. Agr. [^Ijondon^, 6 {1900), No. 4,pp- 465-468). — 

 Good results will, as a rule, be obtained by spraying charlock when not over 3 in. 

 high with a 4 per cent solution of copper sulphate or a 15 per cent solution of iron 

 sulphate at the rate of 40 gal. per acre. Cloudy days without rain give better results 

 than when spraying is done upon bright days. 



The eradication of the prickly pear {Queensland Agr. Jour., 6 {1900), No. 4,PP- 

 319, 320, ph. 2) . — An account is given of the successful use of a spraying solution for 

 the destruction of the prickly pear. The composition of the solution is not given. 



DISEASES OF PLANTS. 



Report of the botanists, G. E. Stone and R. E. Smith {Massachu- 

 setts Hatch Sta. Rjpt. 1899^ j)P- 56-73).— Th^ principal investigations 

 of the authors during the season covered by this report have been 

 contined to problems in vegetable physiology and pathology. The 

 presence of a serious disease in asters is reported, and the authors 

 have begun investigations with a view to ascertain the nature of the 

 trouble and the means for its prevention. Bacterial cucumber wilt 

 has made its appearance in the vicinity and caused serious injury to 

 the crop. In the Annual Report of the station for 1897 (E. S. R., 10, 

 p. 018), the authors described a leaf spot of geranium which was 

 thought to ]je caused by bacteria. At that time it was believed to be 

 the result of al)normal conditions rather than a true disease. However, 

 during the season covered by the report, the disease has been preva- 

 lent and has caused a considerable loss. It causes small yellow dull 

 spots in the leaves, so that they soon fall off and the plant becomes 

 nearl}^ denuded. Examination of the dead spots shows they are full 

 of bacteria, but all attempts to isolate the organism have been without 

 success. 



Failures of the muskmelon crop are reported due to Alternaria sp. 



