These average annual yield figures can be used to calculate the time required to recover expenses and make a profit. One of the obvious observations in the study has been the much greater early life production of cultivars planted after 1954 than those planted before 1955. Those planted later had the advantage of the improved cultural practices that also increased the production of the older trees but at a greater age. The reader should be aware that these older cultivars, if planted under the modern cultural practices, would probably produce better than they did in this study. If a method of chemical or mechanical nut thinning were developed, many of these cultivars may be changed from not acceptable to highly acceptable.
Large nuts are usually preferred, but there are many good small-nut cultivars.
With equal shell thickness, the percentage of the nut volume made up of shell decreases with increasing nut size. Since these periods vary from year to year, more than one pollinator will help assure pollination. Protanderous cultivars shed pollen before pistillate receptivity and protogynous ones are receptive before pollen shed. Actual dates of pollen shed should be used in selection of cultivars as pollinators rather than dicogamy type. The average annual yield of the older varieties was handicapped by the lack of modern cultural practices in their early years.