Desired response1 Concentration of 6-BA (ppm)2 Concentration of Carbaryl (ppm)2 Number of Applications Amount of MaxCel or Cilis Plus Amount of Sevin XLR (L/1,000 L water/ha)
MaxCel (L/1,000 L water/ha) Cilis Plus (L/1,000 L water/ha)
Enhance size only3,4 10–50 2 to 4 0.5–2.65 0.5–2.5
Mild thinning and sizing 50–75 1 to 2 2.65–3.95 2.5–3.75
Moderate thinning and sizing 75–100 1 to 2 3.95–5.3 3.75–5.05
50–75 500 1 to 2 2.65–3.95 2.5–3.75  1
Aggressive thinning and sizing 100–150 1 to 2 5.3–7.95 5.05–7.55
75–100 500–1,000 1 to 2 3.95–5.3 3.75–5.05  1-2
Very aggressive thinning and sizing 150–200 1 to 2 7.95–10.65 7.55–10.1
100–125 1,000 1 to 2 5.3–6.6 5.05–6.3  2

 

— = Information is not available.

1 There are several factors that influence the chemical thinning outcome. Rates are generally chosen on the degree of cultivar sensitivity to chemical thinners.

2 1 ppm is equivalent to 1 mg/L.

3 Mild thinning may occur under some conditions (weak trees, young trees, sensitive cultivars, and environmental conditions that favour the thinning response).

4 While 6-BA has the potential to increase cell division and enhance fruit size beyond the thinning (crop load) effect alone, this is not observed in all years because the response can be affected by spray concentration, coverage, cultivar, tree health, time of application, tree stress, and environmental conditions during and following spray application. Table developed by John Cline, University of Guelph.