Pests & Diseases of Young Orchards
Dani LightleUC Orchards Systems AdvisorGlenn, Butte, & Tehama Counties
© M. Gomes
Insect pests of young orchards
Ken Gray Insect Image Collection
Peach twig borer - Anarsia lineatella
• Pest in almonds
• Direct pest & indirect pest
© D. Lightle 2016
Winter - hibernaculum
Life cycle
© D. Lightle 2016
Winter - hibernaculum
Spring – shoot strikes
Life cycle
© D. Lightle 2016
Winter - hibernaculum
© J. Eves Spring – shoot strikes
4 generations / year
Ken Gray Insect Image Collection
Life cycle
© D. Lightle 2016
Damage to young trees
© D. Lightle 2016
Shoot monitoring
• 1st leaf trees (same year as planting)
• Scout in April
• Consider a May spray if more than 4 shoot strikes / tree
© D. Lightle 2016
Dormant monitoring
• Crotches of 1 to 3 year old wood
• No defined damage threshold• If regularly finding
hibernacula, may choose to treat
© D. Lightle 2016
Dormant monitoring
© D. Lightle 2016
Management – UC IPM Pest Management Guidelines
www.ipm.ucdavis.edu
© D. Lightle 2016
Management – UC IPM Pest Management Guidelines
© D. Lightle 2016
Flat-headed borer – Chrysobothris mali
Ken Gray Insect Image Collection
© M
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Bugg
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.net
Other borers
Walnuts Almonds
Prune limb borer – Bondia comonanaAmerican plum borer – Euzophera semifuneralis
© D. Lightle 2016
Management of tree borers
• Prevent damage by sunburn
• Almonds may require treatment • Look for frass or gum balls• Treat in 6 week intervals while problem continues• Treatment options listed in pest management guidelines
© D. Lightle 2016
Diseases of young orchards
Disease triangleHost
Pathogen Environment
© D. Lightle 2016
Pruning wound cankers – many species
• Affect almonds and walnuts
• Causal agents may include: Botryosphaeria, Phytophthora,Ceratocystis, others
• Symptoms: Gummosis (almonds), cankers (both), branch or scaffold death (both)
© D. Lightle 2016
Band canker -Botryosphaeria dothidea
Trunk and crown cankers – many species
Phytophthora cankers
© D. Lightle 2016
Water
Host
Pathogen Environment
Disease triangle – pruning wound cankers
Pruning wound
© D. Lightle 2016
Water
Host
Pathogen Environment
Disease triangle – pruning wound cankers
Pruning wound
© D. Lightle 2016
Preventing canopy, trunk, and crown cankers
• Don’t prune before rain
• Avoid large cuts when unnecessary
© Glenn Moore Photography 2013
© D. Lightle 2016
Preventing pruning wound cankers
• Don’t prune before rain
• Avoid large cuts when unnecessary
• Keep irrigation water out of the canopy
© Glenn Moore Photography 2013
© D. Lightle 2016
Preventing pruning wound cankers
• Don’t prune before rain
• Avoid large cuts when unnecessary
• Keep irrigation water out of the canopy
• Almonds: Avoid wind cracks by tying
© D. Lightle 2016
Preventing pruning wound cankers
• Don’t prune before rain
• Avoid large cuts when unnecessary
• Keep irrigation water out of the canopy
• Almonds: Avoid wind cracks by tying
• Avoid over-irrigation & over-saturated ground
© Glenn Moore Photography 2013
© D. Lightle 2016
Preventing pruning wound cankers
• Don’t prune before rain
• Avoid large cuts when unnecessary
• Keep irrigation water out of the canopy
• Almonds: Avoid wind cracks by tying
• Avoid over-irrigation & over-saturated ground
• Fungicides will not “cure” infected trees © Glenn Moore Photography 2013
© D. Lightle 2016
Crown gall – Agrobacterium tumefaciens
• Caused by a bacterium
• Affects both walnuts and almonds
• Can girdle young roots or trees
© D. Lightle 2016
Preventing and treating crown gall
Prevention
• Galltrol or similar
• Avoid injuries to roots when planting
• Disinfect pruning shears & never put on ground
© D. Lightle 2016
Preventing and treating crown gall
Treatment in walnuts
• Labor intensive (1-2hrs / tree)
• Excavate roots and expose galls
© Janine Hasey
© D. Lightle 2016
Preventing and treating crown gall
Treatment in walnuts
• Labor intensive (1-2hrs / tree)
• Excavate roots and expose galls
© Janine Hasey
• Physically remove gall (hatchet, chisel, etc)
• Flame edges or treat with bacteriocide
• Leave uncovered for 1 year
© Janine Hasey
© D. Lightle 2016