1. Autumn Defoliation: Effects on Nitrogen, Vegetative Growth, and Fire Blight
Chuck Ingels, UCCE Sacramento County
Jenny Broome, UCCE Sacramento County
Kitren Glozer, UCD Plant Science Dept.
Grower Cooperator: Topper Van Loben Sels

2. Research on Effects of Chelated Cooper + Urea
Used in peaches: fertilize, reduce leaching
N rapidly absorbed, rapidly translocated
Defol. used in nurseries – earlier harvest
Chelated Cu more effective than ZnS04
Cu induces leaf abscission  ↓ N remobilization  ↓ N reserves in tree
Urea acts as surfactant, enhancing copper
Adding urea leads to increased reserve N

3. Defoliation Trial
Defoliant: 1% CuEDTA (Chelated copper, 3.3 gal.) + 2% L-B urea (16.7 lbs.), 100 gpa
Treatments (Dorm. oil sprayed 37 CP)
Oct. 11 (1 CP) 3. Nov. 20 (7 CP)
Oct. 20 (3 CP) 4. Untreated
Randomized complete block design
3 replications of one row each
Treated rows are 3 rows apart

4. Photo Oct. 20, 2007 (Spray applied Oct. 11)4

5. Photo Nov. 20, 2007 (Spray applied Oct. 11)5

6. Measurements Leaves sampled for N content 4/23 & 6/11
Blight strikes counted (none)
Inoculated vigorous shoots with blight 5/28
Weighed prunings to evaluate growth
Surveyed growers about N fertilization
11 growers, 4,300 acres of Bartletts

7. Effects on Leaf N Levels Spur and Shoot Leaves Combined

8. Pruning Weights (4 Trees/Plot)

9. Fire Blight Lesion Length

10. Fertilizers Used by Growers