managing large crop loads final compressed
TRANSCRIPT
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Managing Larger Crop Loads
Byron Phillips • Valent USA Corporation
January 13 • 14 • 15, 2015
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Maximizing Cherry Fruit Size• Fruit Size Determined by:
– Genetic Limitations of Variety– Cell Number– Cell Size
• Cell Number & Size Influenced by:
– Horticultural Practices– Environmental Factors– Hormones (Plant Growth Regulators) & other chemicals
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Maximizing Cherry Fruit Size• Strategies
– Training Systems & Pruning Tactics
– Environmental Manipulation
– Bud Size and Strength
– Pollination
– Nutrition
– Plant Growth Regulators
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Maximizing Cherry Fruit Size• Training Systems and Pruning Tactics
– Different for Precocious vs. Standard Rootstocks
• Mazzard & Mahaleb– Encourage Precocity & Productivity
• Gisela® and Krymsk™– Reduce Crop Load & Increase Vigor
– Training Systems• Open Vase • Spanish Bush• Steep Leader • KGB• UFO • Central Leader• SSA • Free Standing• TSA • Trellised
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Maximizing Cherry Fruit Size
UFO
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Maximizing Cherry Fruit Size
OPEN VASE STEEP LEADER
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Maximizing Cherry Fruit Size
CENTRAL LEADER
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Maximizing Cherry Fruit Size
KGB
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Maximizing Cherry Fruit Size• Pruning Strategy and Tactics
– Keep Fruiting Wood Young & Upright
• Remove all pendant & small diameter wood• Remove spurs > 5 years old• Use thinning cuts for light penetration
– Manage sink: source relationships
• Reducing crop load on precocious rootstocks• Increase fruiting wood on standard rootstocks• Manage vigor with optimum leaf area: fruit ratios• Spur-bearers vs. shoot-bearers
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Maximizing Cherry Fruit Size• Pruning Timing
– Dormant pruning increases vigor
– Summer pruning (after harvest) moderates vigor
– Summer pruning (before harvest) reduces crop load• May be helpful for disease control, but too late to impact
fruit size
– Prune when weather is dry
– Leave stubs if pseudomonas is present
• Prune when bacteria are quiescent• Consider treating tools with quaternary ammonia
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Maximizing Cherry Fruit Size• Pruning Tactics
– Types of Cuts
• Thinning Cuts– Remove pendant wood, weak wood, & improve light
penetration
• Stub Cuts– Branch & spur renewal; new fruiting wood; crop load
management
• Heading Cuts– Stimulate branching, larger leaves (improves leaf area:
fruit ratios)
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Maximizing Cherry Fruit Size• Thinning Cuts
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Maximizing Cherry Fruit Size• Heading Cuts
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Maximizing Cherry Fruit Size• Stub Cuts
Last Year’s Stub Cut
Fruit on shoot below last year’s stub cut
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Maximizing Cherry Fruit Size• Stub Cuts
This year’s stub cut (summer
pruned)
These buds will be large
highest quality cherries
next year.
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Maximizing Cherry Fruit Size• Leaf Area : Fruit Ratios
– Sink : Source Relationships
• Source: Leaf Photosynthesis• Sinks: Shoot growth, leaf expansion, fruit growth; trunk expansion• Fruit growth includes this year’s crop and next year’s crop
– Optimum Leaf Area : Fruit Ratio = 200 cm2 / fruit
• ~ 5 ½ leaves / fruit• Whole Canopy Basis
– Leaf Area by Type
• Non-bearing spurs• Bearing spurs (2X leaf area of non-bearing spurs)• Shoot Leaves (2X leaf area of bearing spurs)
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Maximizing Cherry Fruit Size• Light Penetration
– Training systems & Thinning cuts • Optimize light interception & distribution and photosynthesis
– Shading
• Reduces fruit set
• Reduces fruit size
• Reduces soluble solids
• Delays maturity
• Produces smaller, weaker buds
• Increases weak and dead wood
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Maximizing Cherry Fruit Size• Environmental Manipulation
– Stress Reduction
• Cold Injury (winter)
• Frost Protection (spring)
• Drought Stress – Irrigation amounts and critical times
• Covers– Warmer in spring (cell division period)– Cooler in summer (heat stress reduction)
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Maximizing Cherry Fruit Size• Environmental Manipulation
– Drought Stress
• Water consumption correlated to canopy and leaf area
• Water loss out of cherry fruit regulated by:
– Water needs of leaves (sink)– Temperature– Humidity
• Critical Periods of Water Needs
– Bloom– Cell Division– Stage III– Post-harvest
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Maximizing Cherry Fruit Size• Environmental Manipulation
– Covers
• Increasing use– Rain– Bird exclusion– Temperature moderation & stress reduction
o Warmer temps during spring cell division (Stage I)o Cooler temps during summer heat (Stage III)
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Maximizing Cherry Fruit Size• Bud Size & Strength
– Bud size positively correlated to fruit size
• Largest & Strongest Buds:– Adequate water post-harvest– Optimum light penetration– Young spurs / wood– Good nutrient & CHO reserves going into winter
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Maximizing Cherry Fruit Size• Pollination
– Earliest flowers produce largest fruit• Bee Placement Timing• ReTain Timing
– Flowers from basal buds on 1-year old shoots
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Maximizing Cherry Fruit Size• Nutrition
– Nitrogen• Fall remobilization• Bud size & strength
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Maximizing Cherry Fruit Size• Nitrogen & Carbohydrate Source
– Bud Break, Bloom, Spur Leaf & Canopy Development• N from remobilization• CHO from reserves
– Fruit Growth• N from remobilization Stages I & II; Root uptake Stage III• CHO from current season photosynthesis
– Structural growth (shoots, trunk, roots)• N from remobilization first, then root uptake• CHO from current season photosynthesis
– Remobilization of N in the Fall is Critical• Beware defoliation by deliberately induced phytotoxicity• Post-harvest urea applications
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Maximizing Cherry Fruit Size• Plant Growth Regulators
– Influence Fruit Size by:
• Increasing Cell Division (Cytokinins)• Increasing Cell Size (Gibberellins)
– ProGibb®
• GA3
• END of pit-hardening phase (Stage II) biggest impact on size– Translucent green vs. straw vs. blush
– Potential Future PGR Strategies• Increase Bud Size• Increase Ovary Size
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Thank You