Horticultural News

       
        M. Elena Garcia,  Horticulturist

The apple growing season has begun in Vermont.  Here at the Horticulture Research Farm (HRC) in S. Burlington, full bloom was on May 9th.  This date is 10 days earlier than the average full bloom date of May 19th.  Bloom began with cloudy cool days and with the danger of overnight frost.  Although we had sunny days during bloom,  the temperatures  remained cool during this period.  Some of the blooms did not appear as strong as others.  The only explanation I have for this is the fact that we have not had much rainfall in the past two months.  Root growth occurs at two periods during the season, (1) early spring when shoot growth has not begun and (2) late summer after shoot growth has ended (Fig. 1).  Root growth begins before bud break when the soil temperatures are around 40⁰F. As shoots begin to grow and more carbohydrates and nutrients are partitioned to the shoot, root growth slows.  As shoot growth ends in the late summer when fruit growth slows and the fruit are harvested, root growth begins again until the soil temperatures are not longer suitable for growth. Even though early in the season there were no leaves on the trees to increase evapotranspiration, the warm and extremely dry weather we had during April may have cause the roots to experience a water deficit.  When we were preparing the planting holes for new trees, the top 24 inches of the our sandy soil were rather dry. This stress could possibly translate to poor flower quality.