To insure fruitfulness in nut plants it is generally recommended that
more than one variety of each kind be planted in reasonably close
proximity to help in bringing about cross-pollination. Then, with other
conditions being favorable, the grower would be more certain of good
yields of well-filled nuts.
With specific reference to the filbert, the literature contains
references to the effect that provision for cross-pollination is
essential. However, one exception is listed. In the report of the
proceedings of the 26th (1935) annual meeting of the Northern Nut
Growers' Association, D. C. Snyder of Iowa says on page 47, "The
catkins of Winkler always come through the winter bright and the
variety can be depended upon to bear without other varieties near for
cross-pollination."
The writer has been interested in this subject for several years. The
question arises; how near were Mr. Snyder's Winklers to other varieties
and in what direction with reference to the prevailing winds? It is not
known just how far filbert pollen may be carried and still function. A
planting of Winkler filberts consisting of about 30 bushes was set on
the University Farm at Urbana in 1940. Crops have been borne annually
since that time. The planting was isolated from other filberts to the
southwest by about one-fourth of a mile.
In an effort to determine whether the variety was self-fruitful, plants
were dug in the early winter of 1943 after the rest period was over and
reset in the greenhouse. The plants leaved out in January, 1944, and
both male and female flowers appeared soon after. The pollen was applied
to the pistils both by shaking the branches and by means of a camels
hair brush. Nearly all the blossoms set and the nuts carried through to
maturity. The experiment was repeated in 1944-45 with the same results.
It is therefore concluded that the Winkler filbert is self-fruitful and
may safely be planted alone where climatic conditions are favorable for
filbert production.