Mechanical Pre-Thinning of Cling Peaches Merced County December 2008 Maxwell Norton, UCCE Farm Advisor Dan Rivers, Staff Research Associate

Mechanical Thinning in cling peach, 2005 Kitren Glozer Department of Plant Sciences UC Davis Janine Hasey UC Cooperative Extension Sutter/Yuba Counties

Site 1: Side-mount shaker, computer-programmed for pattern, duration, rate (rpm) Full bloom ~ March 8 First shake date = April 12; even fruit size Moderate crop load

Equipment adjustments tested Changed RPM (range tested) Changed patterns (straight shake, hook, modified hook) Changed durations (½, ¾, 1, 1¼, 1½ sec) Changed weight distribution Changed pads (filled vs flat) Trunk point of attachment (high vs low)

Site 2: April 26 Fruit size variable Fruit too big for shaking (biggest fruit came off) Compare to biggest fruit size to mechanically thin prunes

Results: Shake operation Identify best kind of equipment for shaking: sidemount shaker, computer-equipped, various pad types, wide ability to make adjustments best Identify best equipment settings –Site 1 = hook pattern, 1600 rpm, slightly less than 0.5 sec duration and ‘flat pads’ –Site 2 = modified hook pattern, 1600 rpm, 0.75 sec

Results: Shake operation Identify tree structure differences (e.g. standard- pruned vs renewal wood-pruned) –For both orchards, crop load may have been more important than pruning, since both have hangers and hangers are hard to shake without removing too much fruit from tree top Identify possible modifications to equipment –More weight used at Site 2 might have removed more fruit, so that touch-up hand-thinning would have been less necessary –Maybe a mechanical arm to clamp scaffold at upper canopy would reduce the amount of fruit shaken at top of tree

Summary: Site 1, Renewal wood- pruned May only need 1 shake May not need hand-thin touchup More fruit left on, clusters not all broken, spacing not equal Significantly greater total and salable yield, despite greater undersized yield Cost saving = difference between thinning costs less the undersized yield overage

Summary: Site 2, Standard- pruned With heavy crop may need to shake earlier May need 2 shakes Fruit larger with mechanical thinning + hand thinning than hand-thinning alone –time of hand-thinning didn’t matter –Probably because mech thinning was very early, maximizing the growth curve Total yields not different No significant undersized

2007 Merced Co Mechanical Thinning Trials 19,4-40 (EE) Cordon-trained Hanger-pruned High-density Pedestrian orchard Hesse (EL) Open-vase Hanger-pruned

2007 Procedure Trunk shaker Tried many different patterns, rpm and shake durations “Outside wobble” or “loop” pattern worked best “Sharp” or “star” pattern removed too much fruit 1200 rpm for 2 sec on larger Hesse trees Higher rpm removed too much fruit 900 rpm for 2 sec on smaller 19,4-40s

2007 Treatments Machine thinned both on 4/26 about 45 days after full bloom Hand-thinned rest 1 month later in late May Also touched up machine thinned plots at that time Hesse trees were hand-thinned a third time in early August

Conclusions Trunk shaking not consistent Pre-thinning with the machine may save time and lower the cost of hand thinning Yields were similar at both sites Payoff questionable – depends on block Trunk shaking is problematic Need to take different approaches

Brewt Limb Shaker and Olive Harvester

Olive Harvester

“Olive Shaker” on Tuolumne 2008 Non-replicated, non randomized plot Perpendicular “UC Kearney” V trees Started with 2583 fruit per tree We thinned 18 April Took 1:45/tree Cost about.50/tree Removed 1900 fruit or 2/3 of set Hand thinned 1 st wk May $1.50 Touched up mech thinned trees 24 June for about.50

“Olive Shaker” on Tuolumne Block averaged 24ton/acre Yields between thinning systems the same Sizes similar Saved about.50/tree Heavy sets favor mechanical

Blossom Thinning Loadel 2008 Replicated & randomized plot Traditional, tall vase shaped tree Gloved hand, rubbed blossoms of the top of each hanger using a finger – used a ladder 80% bloom – 14 March Frost in April – grower only broke up clusters Blossom thinning took 23 hours per acre costing about $272/ac using costs from UCCE cost study

Blossom Thinning Loadel Blossom thinned trees yielded about 2 tons per acre more than hand thin but not significant statistically Slight increase in size Even though had frost damage, blossom thinning did not over-thin Another growers tried blossom thinning this year but reported it was too expensive. You will need to experiment.

Thanks to: Brewt Power Systems Britton-Konynenburg Farms Cling Peach Board E & L Farming Elias Cosio Erick Nielsen Enterprises Fiorini Ranch Swanson Farms