BOOKS AND 



BULLETIXS. 



were it not that there exist means for doing well just 

 exactly what the ordinary sprinkler will not do. To this, 

 attenion is elsewhere called." What is this "means?" 

 Why does not the author state clearly just what the 

 method is It is important. The quotation con veys the 

 idea that this ' ' means " is described in the bulletin itself, 

 but the only thing which we can find which seems to 

 warrant the statement, is this sentence on page 9, con- 

 cerning the Vermorel nozzle : " For the cabbage field, 

 nothing can be better, and really satisfactory application 

 can be made only in some such way." The bulletin 

 would have been better if a concise summary of results 

 had been appended. 



Bulletin No. 76, New Jersey Experiment Station. 

 Some Fungous D/sid.us of the Sweet Potato. By Byron 

 D. Hoisted. Pp. jj. Illustrated. This is the first bul- 

 letin to discuss the diseases of the sweet potato, and yet 

 nine definite and serious diseases are described. This 

 is an illustration of the hidden or obscure difficulties 

 with which the farmer has labored, and it is an excellent 

 instance, also, of the manner in which the stations are 

 coming to his aid. The existence of the sweet potato 

 diseases is itself sufficient reason for the establishment 

 of an experiment station in New Jersey. 



The soft rot [Rltizopus nigricans) is most destructive 

 in the store room, although it may be found in the field 

 at digging time. The tubers quickly become soft and 

 worthless. The mould usually enters the tuber through 

 the upper extremity, where it is severed from the main 

 root. " The mould fungus that causes 

 Soft Rot of soft rot is very contagious by contact, 



Swset Potato. as every grower of sweet potatoes who 

 has sufiered from this trouble well 

 knows. It is quite safe to assume that the mould makes 

 its entrance to the root from the surrounding medium, 

 and usually after the roots are harvested. It does not, 

 so far as known, begin by infecting the leaves of the 

 growing plant, and then pass down the stem, as is true 

 with the soft rot of the white or Irish potatoes. That it 

 comes from without the plant, and finds any broken, 

 bruised or cut spot in the root a favorable place for en- 

 trance, suggests the importance of being careful in the 

 harvesting and subsequent handling, that the least pos- 

 sible harm shall come to the skin of the roots. It is also 

 true that the soft rot is greatly favored by a moist atmos- 

 phere, especially shortly after digging, at the time when 

 the roots are undergoing the process known as "sweat 

 ing." At this critical period it is very important that 

 the potatoes be stored in a well-ventilated, artificially- 

 warmed room, that maintains a constant temperature of 

 not far from seventy degrees, or about that of a living- 

 room. Those growers of ' ' sweets " who keep their crop 

 for the late market, or hold the roots until spring, are of 

 one accord, that to avoid the soft rot, a stove or furnace 

 is an essential part of the furniture of the storage cellar. 



The black rot ( Ceratocystis fimbriala) is one of the 

 most destructive sweet potato diseases, and its habits are 

 obscure. It is a dry rot. " The rot begins at a certain 

 point and gradually spreads in all directions, until the 



whole root is decayed. When the patch is of the size of 

 a half-dollar or so, it begins to break up at the center, as 

 indicated by the darker irregular places in the middle of 

 each decayed spot. The black rot is usually evident in 

 the roots at digging time, but many of them are so little 

 affected then that they find their way into the market, 

 and any further loss from the increase of the decay falls 

 upon the middlemen and consumers." The disease first 

 appears upon the young plants, usually in the hot-bed. 

 The shoots are affected with a black rust, and spots of 

 the same stand upon the root. Badly rusted plants are 

 always discarded by growers, but the slightly diseased 

 ones escape attention, and the fungus develops upon 

 them during the whole season. These diseased vines 

 are usually feeble. The disease is communicated from 

 the vine to the tubers. "From the investigation of the 

 subject, it is seen that the black rot 



fungus is abundantly supplied with Black Rot of 



spores, and they may be found in the Sweet Potato. 



one or more forms in every patch 



of diseased substance in the root or sprout. These 

 spores, being formed under ground, as a rule, tend to 

 charge the soil with the germs of infection. How long 

 the spores can remain alive and inactive is not known ; 

 but very likely for many years, and the roots of one crop 

 may become inoculated from the fungus of a previous 

 crop upon the same soil. In like manner, the spores 

 being light as dust can be carried from one field to 

 another by the winds. The difficulties of applying a 

 satisfactory remedy are not easily overcome, for the 

 trouble is so largely underground. In the first place, 

 there is no doubt that only healthy sets should be used, 

 which means the careful selection of perfectly sound 

 roots for the hot-bed. In order to get the best plants, it 

 is possible to use some remedy in the hot-bed, as, for ex- 

 ample, a compound of copper, the Bordeaux mixture, or 

 similar substance which will tend to keep the sprouts 

 from outside contamination. There is also something in 

 the setting of the plants, for if they get a poor start, as 

 from chilling rains, they are weakened, and thereby made 

 more susceptible to the attacks of the black rot. It is 

 not to be considered that the circumstances of the sea- 

 son or conditions of the soil are in any sense the cause 

 of the black rot, as a specific fungus is necessary for 

 that ; but it, like all other living things, is dependent 

 upon its surroundings. It is possible that certain kinds 

 of manure, as heavy cow-dung, for example, are more 

 conducive to the development of the rot than horse ma- 

 nure, and a commercial fertilizer may be better than 

 either. Such questions must be settled by a thorough 

 testing made in the field. It seems impracticable to ap- 

 ply any substances to the soil to kill the germs that have 

 accumulated there. As a rule, the only way is to let the 

 fungus starve out, by withholding the crop upon which 

 it feeds, until the germs become extinct. While a grower 

 with superior sweet potato land may be loath to set aside 

 his best crop, there is no doubt that in some cases, in 

 the long run, it would be the most economical." 



Soil rot [.-\iroiystis halatas] is perhaps the most serious 



