OCR Text |
Show Seed Potato Treatment ay Dr. B. L. Richards, Associate Botanist, Uxperiment Station, Utah Agricultural College Increased activity in seed potato production and certification in the West together with e clearer definlr tion of standards has focused attention atten-tion more definitely upon the potato as a product free from disease and upon seed treatment as an aid In clean seed production. In the process of seed treatment we are concerned primarily with three dlsasea of th potato plant an of wftlch. are serlom in Utah and throughout the Inter-mountain Inter-mountain region : scab, stem canker, (Rhlaoctonia) end Black leg. Tba organisms whidh cause these diseases are ell tuber borne and as such ara Introduced each year into large areas of clean land rendering them unfit for potato production. It la definitely definite-ly known that these organisms when planted with the seed result In a da-creased da-creased yield and in the production of tubers Inferior both for tha market and for seed purposes. Further it must be remembered that the saa and the stem canker organisms onee Introduced Into the soil may live there indefinitely and seriously damage other oth-er and succeeding crops. The disease organisms as they appear ap-pear on tbe surface of the tubers are very resistant to the action ol chemicals chem-icals and rather severe methods are necessary to destroy them. For treating seed potatoes two standard stand-ard disinfectants have been used: formaldehydei one pint to thirty gallons gal-lons of water, and mersurlo chlorldat i ounces to thirty gallons of water, The formaldehyde treatment is not effective against Rhiioctonia at ordinary ordin-ary temperatures and is therefore ot to be generally recommended. Th mercurla Chloride method on the otbeu hand when properly applied has given imlformally good results. A number of precautions are necessary, neces-sary, howeveri in the application of mercuric chloride to the surface of the potato tuber. In the first place it must be recognized that the potato tuber is a living structure and as such Is most resistant to the action ol mercuric chloride wlien in a dormant or resting state. With the earliest signs of sprouting the eyes of thl tubes becomes very liable to injury from this chemical and considerable damage may result in treatment at this particular stage. Early treatment is therefore advisable. Again it has been determined thai damage to the seed may result from the continued action of mercuric chloride if the tubers are allowed to remain wet for a considerable period after treatment. Rapid drying df tha tubers will eliminate this danger and will further add to the effectiveness of the treatment by depositing a slight film of the poison on the surface sur-face of the potatoes. A further protective precaution must be taken against a too rapid reduction re-duction of strength of the treating solution. so-lution. The surface of the tubora rather rapidly absorbs the mercuric chloride In solution as do also tha sacks and any other organic raateria'm that may be introduced with the seed. Where necessary to use 6acks a few should be previously treated for 2 hours in a solution of mercuric chloride chlor-ide and then used repeatedly with successive suc-cessive lots of potatoes. Details for treatment are as follows fol-lows : SELECT only those tubers for treatment treat-ment which are free from burises, daoayed spots and internal browning;. TREAT UNCUT SEED as early as possible in the spring, at least ten days or two weeks before planting. Avoid the use of sacks in treating, Keep seed in a clean place and in sterile sacks after treating and drying. PROPER STRENGTH, Mercuric Chloride, 4 ounces to 30 gallons of water. (1: 1000). TIME OF TREATMENT. Dormant seed 1V4 hours. If tubers have started to sprout and show but little disease reduce the tlmej but in all cases soak the seed for at least hour. Soaring Soar-ing for 24 hours in cold water before treatment will greatly aid in destroying destroy-ing the disease germs. DRY POTATOES as rapidly as possible pos-sible after treatment- For early crop, where convenient "green" the tubers In the sun for a few days toefor planting. plant-ing. KEEP UP STRENGTH OF SOLUTION SOLU-TION by adding 3-8 ounce of mercuric chloride after treating each four bushels of potatoes treated for one and one half hours and restore the volume of water to its original 30 gallons. gal-lons. DISCARD SOLUTION after the third or fourth treatment where no chemical Is added. It Is also necessary neces-sary when chemical Is not added to increase tha time of treatment 15 minutes for each consecutive lot treated. treat-ed. MERCURIC CHLORIDE A DEADLY DEAD-LY POISON. If taken internally. Mercuric Chloride Is a deadly poison. Keep from all farm anlmai3 nnd from children. Mercuric chloride hus neither neith-er tast, odor or color and Its solution solu-tion may easily be mistaken for pure water. MERCURIO CHLORIDE CORRODES COR-RODES ALL -PROTECTED METALS. MET-ALS. Use wo-k1 or cement containers luch as bnrre.s or tanks. Galvanized iron tanks may t used if protK-te Tib esphnltnni pclnt. |