Resistance and Immunity
Some plants can tolerate the presence of large numbers of insects without being severely affected. This is not very satisfactory however as insects will still cause damage, and in fact further breeding and population expansion of the pest species is supported. Other varieties are less attractive to pests, but this can be difficult to sustain or demonstrate.
The most valuable form of resistance is where the pest cannot survive as well on one variety as on another. In some cases this can actually make the plants immune to attack, as is the case with the lettuces Avoncrisp and Avondefiance which were bred at the Institute of Horticultural Research, Wellesbourne during the 1960s, which are fully resistant to lettuce root aphid (Pemphigus bursarius).
Read more about this topic: Disease Resistance In Fruit And Vegetables
Famous quotes containing the words resistance and/or immunity:
“He made no resistance whatever, and was stabbed in the back.... I must not dwell upon the fearful repast.... Words have no power to impress the mind with the exquisite horror of their reality.”
—Edgar Allan Poe (1809–1849)
“There is immunity in reading, immunity in formal society, in office routine, in the company of old friends and in the giving of officious help to strangers, but there is no sanctuary in one bed from the memory of another. The past with its anguish will break through every defence-line of custom and habit; we must sleep and therefore we must dream.”
—Cyril Connolly (1903–1974)