Abstract:
Pea streak virus (Marmor trifolii Holmes) is widespread and
occasionally destructive in Eastern Oregon and Washington, and in
many other pea growing areas. Since control by the use of insecticides
to kill the insect vector is only partially successful, resistant
varieties of peas are needed.
In a study to confirm the mode of inheritance of resistance to a
strain of pea streak virus (PSV), resultant data suggested that resistance
is governed by a single recessive gene. Resistant plants
were infected and supported a substantial virus concentration, but
were symptomless. The virus concentration in resistant plants, as
determined by local-lesion assay in Chenopodium amaranticolor,
approximated that of plants showing severe symptoms.
The effects of various environmental factors on symptom expression
by several types of peas were studied to facilitate studies
and breeding. The symptom expression was affected by seasonal
change, soil fertility, and plant growth conditions. Plant height was
reduced by PSV infection in susceptible varieties but not in the symptomless
or resistant type of plants. Symptom expression was more
pronounced when plants were grown in soils which did not favor vigorous
growth. When growth was reduced by chemical retardants or
excess fertilizer, symptoms were more pronounced.
