BOOKS AND BULLETINS. 



695 



white flowers, and growing on cool ledges along the Rio 

 Grande de Santiago. 



The labors of Mr. C. G. Pringle are indelibly asso- 

 ciated with the botany of Northern Mexico. For a 

 number of seasons he has collected there, and numbers 

 of plants have been named for him. There are twenty- 

 one with the specific name PringUi in the present enu- 

 meration. 



Seventh Annual Report of the Massachusetts 

 Experiment Station for 1889. In this report Professor 

 Humphrey gives an account of some experiments upon 

 potato scab. The following are results of field treat- 

 ments : "I. Deep planting appears to tend to dimin- 

 ish the development of scab, though further experiments 

 in this direction are very desirable. 2. While the very 

 dark potatoes were wholly free from scab, 

 Potato little or no difference was to be noticed in 



Scab. the susceptibility of the three light vari- 



eties planted. 3. The potatoes raised on 

 barn-yard manure were markedly more scabby and more 

 deeply scabbed than the rest. 4. Tobacco dust in the 

 drill had no appreciable eflect in increasing or dimin- 

 ishing the scab, 5. Scabby "seed" produces a crop 

 neither better nor worse than that grown from smooth 

 potatoes." Professor Humphrey distinguishes two 

 forms of scab, the ' ' surface " and the ' ' deep." "It is 

 certain that our disease is the same as that discussed by 

 German writers, and that it is not caused by any para- 

 sitic organism. Several years' observations at this sta- 

 tion point, also, to the correctness of the view that the 

 cause of our trouble is to be sought in peculiar physical 

 or chemical conditions of the soil, though the opinion 

 that excessive moisture is a sufficient controlling cause 

 seems hardly tenable." 



Annual Report of the Connecticut Experiment 

 Station for i88g. This volume of nearly 300 pages is 

 especially rich in fertilizer tests and analyses. The parj 

 which particularly concerns the horticulturist is the re- 

 port of Roland Thaxter, the mycologist. Dr. Thaxter 

 has made a particular study of the diseases of onions, 

 and has reported upon them here at considerable length 

 The worst onion disease in Connecticut is the smut 

 {UrocysHs Cepiihe). "The presence of smut in onions 

 is first indicated by one or several dark spots at differ- 

 ent heights in the leaves of seedlings, which are seen to 

 be more or less opaque when the plant is held up to the 

 light. These dark appearances may be seen in the first 

 leaf, before the second leaf has begun to 

 Onion develop at all, and are more commonly 



Smut. found just below the ' knee ;' though they 



sometimes occur above it. After a time, 

 usually while the second leaf is developing, longitudinal 

 cracks begin to appear on one side of these spots, which 

 widen and show within a dry, fibrous mass, covered with 

 a black, sooty powder made up wholly of the ripened 

 fruit or spores of the fungus, which are blown or washed 

 out onto the ground. In some cases the smut may ap- 

 pear only toward the upper end of the first leaf, and 

 become cut off from the main body of the plant by the 



withering of the former. In such a case an onion which 

 has shown smut in its first leaf appears, m some instan- 

 ces, to recover, showing no signs of smut in its subse- 

 quent growth ; but as a rule the same dark appearance 

 shows itself in the second leaf and those subsequently 

 formed, and if the seedling is pulled up and examined, 

 the whole plant will be found to be pervaded by the 

 disease to a greater or less extent. Plants thus diseased, 

 especially if the soil is dry, very commonly succumb 

 early, dying while in the second or third leaf. The 

 stronger plants, however, especially if the ground is 

 moist, are able to resist the smut sufficiently to make a 

 considerable growth, and may survive even up to the 

 time of harvesting." 



Several substances were drilled into the ground with 

 the seed to destroy the fungus, such as sulphate of iron, 

 a patent " germinator, " sulphide of sodium, hyposul- 

 phite of sodium, sulphate of copper and sulphur mixed 

 with lime. The sulphur and lime mixture proved to be 

 the best remedy, all things considered, and it was a de- 

 cided benefit to the plants treated with it. Equal weights 

 of sulphur and lime were mixed, and 5 grammes (about 

 3}2 pwt.) of the mixture was sown in the drill in 10 feet 

 of row. Some excellent plates are given, representing 

 the experimental plots, and of the structure and natural 

 history of the fungus, 



The onion mildew [Pero?iospora St /i/eii/r/ii), known also 

 locally but erroneously as " white blast," has seriously 

 damaged fields of seed onions in Connecticut. 



' 'An examination of the affected stalks showed that the 

 trouble originated as a small yellowish discolored patch, 

 usually on one side, from which the disease spread in 

 all directions so as often to involve the whole stalk. The 

 only visible appearance upon the the sur- 

 face was an obscure, mould-like coating. Onion 

 white near the edges of the diseased spot. Mildew, 

 and slightly reddish near the center. 

 This appearance of mildew was also noticeable on such 

 leaves as had not been already entirely killed by it, and 

 was very commonly followed by a velvety black coating, 

 sometimes covering the stalks almost entirely and form- 

 ing a conspicuous feature in the diseased fields. This 

 black appearance is due to a fungus [Macrosporiinn) 

 wholly unconnected with the mildew." 



This disease is well known in Europe, and it is exceed- 

 ingly destructive in Bermuda. It attacks the market 

 onions as well as the seed crop. All infested onions 

 and leaves should be burned in the fall, and the planta- 

 tion should be removed to a fresh field. It is probable 

 that some of the sulphur fungicides, applied early in the 

 season, will be beneficial. 



Other diseases of the onion are discussed, particularly 

 two macrosporiums and a vermicularia. 



A new species of mildew (named Phvtophtlioia P/itutoli 

 by Dr. Thaxter) has seriously attacked 

 lima beans in Connecticut. This is an Lima Bean 

 interesting discovery from a scientific as IVIifdew. 

 well as from a practical point of view, 

 as there are only two other species of phytophthora 



