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Show I POTATO DISEASES IN IDAHO Harry B. Shaw, federal pathologist, who for three years was stationed at Ogden. Is now at Jerome. Idaho, studying potato diseases. He has Issued Is-sued a bulletin on his Investigations in the potato fields of Idaho In which he makes these observations. "A tour over the principal potato growing districts of Idaho and In Inspection In-spection of potato cellars and pits during early spring of the present season revealed the presence of an amount of diseased potatoes alarm lug. The most 6erlous and prevalent disease was the powdery dry rot. About equally prevalent, but less destructive, de-structive, was Rhizoctonla scab The common potato scab was nowhere lound to be abundant. At the close of this tour suggestions sugges-tions were offered for the i-election and treatment of seed potatoes prior to planting hints were also given for the choice nnd preparation of ground In which to plant selected tubers Tb I potato growers were cautioned to se-I se-I lect only seed potatoes entirely trl from symptoms of dllMtfea, most cure-fully cure-fully culling out any showing rotted areas, not even using the apparently sound portions of such tubers. This advice was chen because the planting of potatoes thus diseased J would inevitably Infect the ground In which they were planted and. although al-though cuttings affected with dry rot 'I might In many cases germinate and bear sound potatoes, a pocket of Infected In-fected soil WOUld be created, and the ' germs or spores of the disease-producing fungus would probably COtnO , In contact wlih. and remain upon th surface of any potatoes obtained I from diseased cuttings Should conditions con-ditions be favorable these spore would germinate In bruised places on potatoes In storage. "The powdery dry-rot is caused by a fungU6 which attacks potatoes In storage Although the spores of th fungus mav be present upon the tubers v hen harvested, fnoy lr.ip not I at that time produced any rot. This j fungus attacks the potatoes during I storage, chiefly through wounds in j the skin, whence under foVorablfl j moisture ami tetnpftrtturt conditions 'it may develop rapidl;- until Hie In-I In-I footed potato becomes wholly or In 1 pari rotten and conveys the disease to other potatoes Unfortunately for us, this fungus, which, like othei ! plants, requires a certain amount of heat and moisture for Its development. develop-ment. lg capable of growing at th comparatively low temperature of 37 j degrees F. and Is generally able to I I obtain moisture enough from the I mass of stored potatoes, especially it the cellar be not well ventilated. "Once Infected with this and some other fungus diseases, the soil requires re-quires several years to become rid ot the disease germs and they only when no crops suspectlble to these particular germs are grown there. Therefore a rotation of four or five years should always be practiced. There Is land enough available to do this even whore potatoes nro most extensively grown It is safe to predict pre-dict that if this and careful seed selection se-lection be not practiced a fate similar to that now po greatly reducing the yields of one of Colorado's great potato po-tato districts will overtake the potato pota-to districts of Idaho "As for the common and Rhizoctonla Rhizoc-tonla scabs. It was recommended that seed potatoes be treated with R solution of formaldehyde. 1 pint (40 per cent) to 30 gallons of water for 2 hours, or fumigated with formic acid gas generated by pouring 40 per cent formaldehyde upon permanganate perman-ganate of potassum In the following proportions: "Formaldehyde (40 per cent) 3 pints. Permanganate of potassium 23 oz "This amount to be used for every 1000 cubic feet of space In the cellar, cel-lar, which should be closed for at least 24 hours, at a temperature of not less than 60 degrees FY' oo |