Scab Screening Nursery

Scab Screening for Lakota X 87MX3-2.11.

Picture by Dr. LJ Grauke.

February 27, 2019

In 2017, controlled crosses were made on multiple ‘Lakota’ trees in multiple orchards in Georgia and Texas using pollen of 87MX3-2.11 for development of shared mapping populations. Nuts were harvested, individually numbered, and measured. Nuts were planted into treepots. Seedling emergence was recorded daily, and diameter and height measures were collected in early June 2018.

Seedlings from each orchard were randomized across the 6 racks of the nursery by assigning 21 plots/ rack and placing a 9-pot crate from a specific orchard in each plot. Plots on each rack were designated for control seedlings (grafted seedlings of ‘Lakota’ and 87MX3-2.11).

In order to induce an epidemic of scab for seedling inoculation, rainwater collected from the roofs of unit structures was plumbed to the nursery. Telephone poles erected at each end of the nursery were used to support an irrigation line with a sprinkler emitter positioned over the center of each set of scab susceptible selections. Overhead sprinkling occurs twice nightly for 5 minutes, wetting the canopies to drip point falling on seedlings below.

Seedlings were rated for scab expression in August. Statistical analysis indicated that significant differences were observed in scab infection between the mapping populations based on geographical origin of the cross. Further research is in progress with these mapping populations.