Friday, October 10, 2014
Air movement and scab infection
Down in the Bootheel of Missouri I found that air movement within a single tree's canopy can also impact scab infection. The photo above shows two clusters of Faith pecans; a scab infested cluster at the top and a relatively clean nut cluster at the bottom. Note my hand in the photo. I was holding the scab infested cluster next to the clean cluster so you can see how scab infection inhibits nut size.
The scab infested cluster was originally located on a lower, interior limb. The clean cluster was out in full sunlight and fully exposed to drying winds.
This Faith tree is fairly young and was weighted down by a heavy crop of nuts. Limbs on the tree hung low which prevented good air movement under the tree and trapped moisture on lower interior branches. This trapping of moisture provided optimal conditions for disease spread leading to a localized scab outbreak on interior limbs. As this tree grows larger and lower limbs are removed, air movement through and under the canopy will improve decreasing the conditions for this type of scab problem.