the same mixture as is recommended for
apples--five pounds per 100 gallons of spray mix. These trees were
observed weekly, and by late August had made more growth and gave better
response than trees in comparable unsprayed rows. As the walnut trees
are of different varieties, no definite comparisons may be drawn, but
the trees so sprayed outgrew the unsprayed plot, although both plots had
received a spring application of fertilizer of equal amount.

Set of Fruit Depends on Pollination

The best yields of fruit are found on trees that have a good pollinator
close by. Oftentimes the catkins of the Persians dry up, fail to shed
pollen when the pistillate flowers are receptive or fail to produce
staminate flowers. It was noted early this spring that the catkins on
the Persians were very few. Pollen was gathered from the butternut
(_Juglans cinerea_) for pollinating the pistillate flowers that opened
early. The mid-season flowers were pollenized with black walnut
(_Juglans nigra_), and the later blooms were fertilized with pollen from
the heartnut (_Juglans sieboldiana cordiformis_). Many of the pistillate
flowers were bagged and remained receptive for a long period.

The best set of fruit on trees this year is on trees that have either
the black walnut or the heartnut near by as pollinizers. The pollen from
the butternut seemed to dwarf the fruit size on those trees where the
pistillate flowers were bagged in the Purdue planting. We have little
doubt that the Persian walnut develops a preponderance of pistillate
flowers and relies on pollen from kindred species for a good set of
fruit.

Nut Displays Have Educational Value

The interest in the Persian walnut in Indiana has developed to the
extent that several commercial fruit growers have set out small
acreages. Most of the trees are seedlings from trees previously fruited,
although several growers have budded or grafted the better seedlings on
the native black walnut. The public has become enthused through the
various displays at local and state fairs and through the state nut show
now being held annually. The exhibits have brought out some very
desirable seedlings, each listed under the owner's name. Some of the
seedling nuts have averaged about two inches in diameter, and 12 year
old trees have produced as much as 50 pounds of cured nuts.

The largest Persian walnut tree found in Indiana is at Lafayette, it
being 12 inches in diameter and possibly 40 feet high.