HAIRY-VETCH SEED PRODUCTION. SUL 
hard seed decreases with age. Hard seed is not especially objection- 
able where hairy vetch is grown year after year on the same ground, 
as these seeds will germinate during succeeding years. Where hairy 
vetch is used in a rotation, however, it is very desirable to have the 
seed germinate the same year that it is sown. 
The percentage of germination of seed of different ages and the 
relative amount of hard seed are shown in Table III. These data 
are taken from germination tests made at Corvallis, Oreg., by Mr. 
“HA: Schoth. 
TaBLE III.—Germination and hard seed of hairy-vetch seed of different ages grown in 
different years.* 
Germination test madein October. 
Year seed was 
grown. 1915 1916 1917 1918 1919 
Germi-| Hard | Germi-} Hard | Germi-| Hard | Germi-| Hard |Germi-| Hard 
nation.| seed. |nation.| seed. |nation.} seed. |nation.| seed. |nation.| seed. 
Ob ace acacdamnaocoe 11 89 38 60 70 29 67 33 67 29 
IQND SS. SonsSoceSSesoaloasscoud|lbaesuses 84 16 90 10 87 13 85 12 
IU SsbosScedhsesenesl| Seoscess| Saseesea leseaones| |aoscesoe 88 11 88 11 S84 13 
Ne) Setooscbeacesoeal SSs5q0cs|ooooSe ed socoenes Sppeeeor Soncdeod sae seers Seecs ane laa aaa ae 82 18 
1 The germination tests were made in duplicate, using 100 seeds in each test. 
The seed of hairy vetch retains its vitality for a number of years. 
Seed 5 years old will usually show but little, if any, deterioration. 
INSECTS. 
Until quite recently hairy vetch was considered almost immune 
from the attacks of insects and fungous diseases. One of the few 
, insects that injure hairy vetch to any extent is the pea aphis ( Mac- 
-rosiphum pisi), which attacks the plants during the blossoming period 
and sucks the juices from the stems and leaves just as the seeds are 
setting. In wet seasons and in heavy rank growth the aphids some- 
times appear in great numbers and almost destroy the vines before 
their presence is suspected. Fortunately, aphids cause much less 
damage in the thin, open stands which are the most profitable for 
seed production. The injury from aphids is most likely to occur on 
heavy soils where the crop is grown for hay. No practical means of 
control is known. 
In the cotton belt, especially along the Atlantic coast, hairy vetch 
occasionally is injured seriously by the common cotton bollworm 
(Chloridea obsoleta). 'The invasions of this insect, when taken in time, 
are easily combated. They are most likely to occur during the spring 
months before the other host plants of the insects are available for 
food. Where the cotton bollworm attacks hairy vetch, the most 
° Prepared with the advice and cooperation of W. R. Walton, Entomologist in Charge of Cereal and 
Forage Insect Investigations, Bureau of Entomo!ogy, United States Department of Agriculture. 
