Show CONTROL THE POTATO SCAB select clean disease tree free seed potatoes treatment Is an added precaution the treatment of seed potatoes with formaldehyde or with corrosive bubil mato lias has been recommended tor for many years as a preventative of acau scao anil and other diseases carried on the tubers such treatment Is on the whole profitable but has several limitations which should be clearly reco recognized 9 to prevent disappointment according to the specialists or of the department the object ot of dis infecting seed pota potatoes tores is to destroy the germs of scab and uther other surface parasites which might otherwise be planted with the seed and infect the new crop only surface infections factions are reached by title this it Is only partially effective against deep pits of common scab formaldehyde Is less effective than corrosive sublimate against the black otla or resting bodies of or russet scab and against powdery scab neither chemical as ordinarily used will destroy silver litner dulier one will kill surface infections of blackleg but neither will reach the internal infections common in tubers from blackleg hills neither wilt por late blight infection in potato tubers can an be reached by any seed berat ment nor can any of the nou parasitic diseases of potatoes such as mosaic ceaf roil and curay dwarf be prevented see farmers bulletin tor for description of these troubles clearly therefore the most import an precaution against these diseases li iq to select clean disease tree free seed potatoes from healthy vigorous plants as determined by field inspection during the growing season and at harvest barvest sled seed treatment should then be applied as an additional precaution it will not be effective however if the soil sail where the potatoes are to be planted Is 13 already full of disease soil conditions and potato diseases soil conditions have an important tant relation to potato tuber diseases and many of these are widely spread throughout the country perhaps native top to some soils common scab is favored by a neutral or slightly alkaline soil and seldom gives trouble in acid soils it is therefore increased by liming and by fresh stable m manure anure wood ashes and alkaline fer fertilizers such as nitrate of soda and brouna ground bone while acid phosphate and sul chate of of ammonia tend to diminish scab occurs to some extent in nearly all soils but appears to attack potatoes most when uie the conditions are unfavorable to the best development of the potato plant brin bring 9 the land to an ideal state stale 0 of to nAni minimize mize loss from powdery scab Is worst on cold wet or poorly drained soils blackleg on an tho the other hand is carried by infected seed no potatoes showing a deep brown discoloration at the steam end should be ba planted sulphur tends to prevent common scab it is not a substitute for corrosive sublimate or formaldehyde but is a good drier tor for cut seed applied to scab infected soils at the rate of pounds per acre it reduces the scab but such heavy application can not be generally recommended as profitable preliminary experimental trials are advised how to disinfect seed the formaldehyde treatment consists in soaking the potatoes before cutting for two hours in a solution made by adding I 1 pint of formaldehyde to 3 30 gallons of water the solution can be used repeatedly the gas treatment Is no longer recommended rl ded corrosive sublimate is use used d at the rate of 1000 1 tor for one and ane halt half to two hours dissolve 2 ounces of the salt in liot hot water v ater and dilute to 15 gallons I ilo as this is a deadly poison use with care it must also be kept in wood porcelain or glass vessels as it attacks metal it is more effective than formaldehyde particularly a and scab do not use the same solution more than three times as the strength diminishes minis hes with each lot ot of potatoes soaked to treat largo large daan quantities set several barrels on a slightly elevated plat agia fit a plug in a hole in the bottom of each barrel fill with potatoes cover with solution let stand two hours draw off solution and pour into another barrel increase the number of barrels in proportion to the quantity to be treated another method s to use a large wooden vat or trough nto into lowered which the potatoes in sacks are lowered by a rope ropa and pulley and later hauled out drained and dried on slatted racks seed potatoes may be treated several weeks before planting provided they are not re infected by storing in old containers or storage bins sprouted potatoes are injured by treatment but will throw out new sprouts in general however potatoes t will not be injured by following the above directions many growers believe germination is improved by treatment |