Flowering Response
Each year at the height of the flowering period, each tree in the experiment was rated on the catkins it carried. So far, there has been no effect of the differential fertilizer treatments on the production of catkins. However, there have been very highly significant differences between the Potomac and the Reed. In 1950, only four of the 36 Reed trees produced catkins, whereas 32 of the 36 Potomac trees flowered, and approximately half of them were heavily loaded. In 1951, the number of Reed trees producing catkins was 12 of the 36, whereas 35 Potomac trees flowered. The amount of pistillate flowering during the two years was small on both varieties and not greatly different; this indicates that their nut-bearing potentialities may be about the same. The amount of pollen produced by the Reed variety has always been considered ample for cross-pollinating the Potomac, even though the former has been a light producer of catkins.
Records of dates of flowering of the two original trees over a 10-year period, and of these young orchard trees over a 3-year period, show that there is great variability in time of flowering, depending upon the sequence of weather events each season. Fertilizer treatments have had no measureable effect. The trees have shed pollen as early as January and as late as April, and stigma receptivity sometimes has continued intermittently for two months. The average period of flowering at Beltsville is the last week of February to the first week in March. Both varieties have flowered at the same time under all seasonal conditions observed. This means that additional pollinators will not be necessary when the varieties are planted together in an orchard.