2019 ASHS Annual Conference

While olives are native to the warm, dry summers and mild, rainy winters of the Mediterranean region, they can be successfully grown in areas with mild winters in Texas. However, occurrence of frequent freezes can damage olive plants, most severely on young plants. An olive orchard was established at Sam Houston State University’s Gibbs Ranch in March, 2016. Low temperatures encountered in January 2017 killed many of the recently established plants and severely damaged others. This study analyzed the effects of soil treatments on the growth of the surviving, but badly damaged, trees and the new, pot-grown trees used to replace those that died due to freeze damage.

Twenty-five olive trees planted in 2016 that survived the 2016-17 winter with minor freeze damage (Old) and twenty-five newly planted replacement trees (New) were selected. The following treatments were randomly assigned to the two classes of trees (Old and New) with five replications (individual trees) of each treatment.

• Control
• Fert: 16-6-12 and 20-20-20 Osmocote fertilizer
• Compost+BM: Mushroom compost + Blood Meal
• Fert+AMF: Fert + Mycorrhizae
• Compost+BM+AMF: Compost + BM + Mycorrhizae

Measurements of plant height and stem diameter were taken ten times from 6-3-17 to 10-7-17 at 14-day intervals on each of the 50 trees. Treatment effects were assessed using the Analysis of Variance (ANOVA) for Completely Randomized Design. Stem diameter increases for both Old and New plants was greatest with the mushroom compost + blood meal treatment. The 16-6-12 plus Osmocote treatment provided the greatest increases in plant height for the old plants, but was similar to that of the control group.