Growing Pains: When some young walnut trees turn yellow and don't grow, look out below

摘要

WHEN an individual young walnut tree turns yellow compared to all of its neighbors, it often indicates that there is something going wrong in the root system. There are a variety of potential causes for these symptoms and we can't explore all of themfully here, but we'll try to comment on some of the main things we see on farm calls. One of the more common problems has been water logging injury due to either excess irrigation or periods of excessive rainfall sometime during the past two years. Whenwalnut roots are excessively wet they can die from lack of oxygen even without any major pathogens present. Rain during fall 2007 could have been a problem for some trees in young orchards that made good growth up the stake the first year (2006), made good growth the second growing season (2007), and were pruned back last dormant season, but either didn't grow this past spring or made very weak growth in 2008.