vStudies of Healtfi in Potatoes. 
(causing lack of aeration) are joint factors adverse to health oi 
potato roots and plants. iThese factors were in direct relation to 
the presence or absence of Fusarium hyphae in the water tubes. 
Irrigation practice and experience also prove that heat and soakage 
are adverse factors that should not be combined. 
Field studies of sub-irrigation indicated, in a certain sandy 
loam, that three feet was the best depth to water, and that a higher 
water level was injurious and a lower level insufficient. 
indifferent results were secured by shading and by covering- 
plots of potatoes with glass. 
Deep cultivation is approved by practice, by field observations 
and by experiment as a means of protecting potato roots from ex¬ 
treme temperatures. 
The temperature of irrigation water varies widely, and is an 
important factor because of its high specific heat as compared to 
that of potato soils. Cold, pure water is best for potatoes. 
We have had new ground for potatoes in settling up a new' 
country and a new State. Many districts have become quickly 
unable to grow potatoes at all, the heavier soils in warmer regions 
going out first. 
There has been conclusive evidence, in-the-large, that the leaf- 
roll in Colorado, in addition tO' heat and soakage, had an infectious 
or fungous factor. 
Cabbage plants, resistant to similar conditions, are readily 
secured thru selection and their culture is successful in a commercial 
way on “sick” land. No resistant plants among potatoes were seen. 
Only a few sorts of potatoes are grown, and hundreds of thousands 
of seedlings would be necessary for the selection of resistant plants. 
Almost no pollen was found except on the Pearl bastard, under 
leaf-roll conditions. 
Seedlings, when secured, could not be developed successfully 
under leaf-roll conditions. 
General Summary .—In potato health, soakage, close-grained 
soils and poor aeration of soils give the sarnie results. Soil heat, 
poor aeration, and infection are the three factors adverse to health 
in potatoes. The less a district has oif one adverse factor, the more 
it can stand the other two. The more open and cool a soil, the better 
it is adapted to potatoes; the heavier, damper and warmer a soil is, 
the poorer is it adapted to potatoes and the quicker will the crop fail. 
Regions having fair conditions for health of potatoes can only 
hope to grow their crop permanently by planting a very small pro¬ 
portion of the area in this crop each year. 
