AgFax printed a story from UGA scientist Lenny Wells on the impacts of microclimate on pecan production.  You can read the article here.

The impacts of the site on which the trees are planted is important in how likely the trees are to be affected by scab, which can seriously impair the trees’ ability to produce good crops of nuts.  Low elevations surrounded by trees are especially prone to disease because of the limited ventilation from wind and the extra moisture provided by the surrounding trees.

Source: USDA via Commons Wikimedia
Source: USDA via Commons Wikimedia
Source: Yuva Segal, Commons Wikimedia
Source: Yuva Segal, Commons Wikimedia