A BACTERIAL STEM BLIGHT OF FIELD 
AND GARDEN PEAS 
By WALTER G. SACKETT 
INTRODUCTION 
Before the introduction of alfalfa into the San Luis Valley, 
field peas were grown very extensively as a leguminous crop for 
feeding purposes. Aside from their value in this role, their use in 
a crop rotation as a means of restoring partially the soil fertility 
lost by excessive and continuous cropping with small grains, was 
soon recognized. 
For a number of years peas were used almost exclusively as 
the forage crop, and the acreage planted was very considerable; 
however, some five or six years ago. it was found that alfalfa could 
be grown successfully nearly everywhere in the valley. It suc¬ 
ceeded very well for the first two or three years, but in 1914 , follow¬ 
ing a heavy, late spring frost, the crop was attacked by the bac¬ 
terial stem blight which reduced the tonnage of the first cutting 60 
to 80 percent, to say nothing of the injury resulting tO' the plants 
themselves. Since then there has been a recurrence of the disease 
each year with varying degrees of severity. Quite naturally, with 
the appearance of this new trouble, the feeders may have to turn 
their attention more largely to field peas, but let us hope not to the 
exclusion of alfalfa.' 
Practically all of the cultivated land in the San Luis Valley 
lies at an elevation of between 7,500 and 8,500 feet, and at this 
altitude the temperature usually remains cool until well into the 
summer; frosts may be expected any month of the year. The soil 
is a sandy loam for the most part, and there is an abundance of 
irrigating water. 
The pea being a lover of cool soil and cool weather, it is dif¬ 
ficult to conceive of a location where conditions are better adapted 
to pea growing than in this old lake basin. For years they have 
been raised here to perfection without the first complaint of any¬ 
thing in the way of a bacterial, fungous or animal pest. But it is a 
long road that has no turning, for in the spring of 1915 the peas 
over almost the entire valley, which includes some 500,000 acres, 
were attacked by a disease:, previously unknown in the community, 
and which at the time threatened to be even more serious than the 
alfalfa blight. 
