Download Station 1: Arbutus and Garry Oak

Station 1: Arbutus and Garry Oak
Arbutus
Facts
 Only distributed in SW corner of BC; grows south to California.
 Common on well drained southern exposures; flowers in mid-Spring with clusters of white
flowers.
 Have red peeling bark, shiny evergreen foliage, and persistent red fall berries.
 Not difficult to grow, very difficult to transplant.
 Prefers full sun, dry conditions, and sandy or gravelly soils with good drainage.
 Intolerant of compaction, disturbance, shade, poor air flow.
Propagation
 There is the perception that it is difficult to cultivate arbutus, but MICS has had success.
 Step 1: Collection- Each fruit has approx. 8 or more seeds. The fruit needs to be ripe (deep
orange/red); often ready in later fall/winter. It’s best to gather after first big fall/winter
windstorm where lots of fruit will be on the ground. The birds enjoy so don’t wait too long.
 Step 2: Preparation- Separate fruit from stem, cover with water in a Ziplock bag for about a
week until the fruit softens. In sink, squash the fruits by hand over screen (e.g. mesh strainer)
with bowl underneath. Run water over the flesh so that seeds are washed through the screen
into the bowl beneath. Then pour off water so that seeds are left behind in bottom of bowl.
Place seeds on dry paper towel to dry.
 Step 3: Cold Stratification/Germination- Option 1: Leave seeds outside on fine seedling mix
(maximum .25cm of soil over top) in 1 gallon pots during the winter, exposed to elements.
Option 2: Mix seeds with a moistened, fine seedling media mix in lidded container. Place mix in
fridge for 40-60 days. Once the seeds have germinated, put seeds outside on fine seedling mix
(maximum .25cm of soil over top) in 1 gallon pots.
 Step 4: Potting up/dividing- Don’t do until at least 2-4 true leaves appear. It is best done in
cooler weather so the risk of drying out is minimized. Gently tease seedlings apart, keeping as
many roots intact as possible. Plant one seedling per pot, adding more medium to new pot
until soil is at same level on seedling as before. In other words, hold the top of the seedling
above an empty pot with the long taproot hanging to the bottom of the pot as you slowly and
gently fill the pot with soil with the other hand.
 Step 5: Outplanting- When outplanting, dig holes 2 times the diameter and depth of the
rootball, deep enough so the plants are at the original soil level. Arbutus are adapted to dry
summers, if you regularly irrigate them they will not grow deep roots and will be susceptible to
drought. Only water them during long droughts (give them a deep watering once a week
during the summer drought in the first year). The ideal time to plant arbutus is October and
November so that roots can establish over winter. When outplanting do not stomp on soil
around plant; you want to have loose, ventilated soil to provide roots with oxygen. Protect
from deer.
Diseases
•Foliar fungus diseases are common as is leaf insect activity, but they are mostly cosmetic
unless repeated defoliation occurs. Winter winds, damp winters and springs often blacken last
year’s leaves, which shed in July leaving current healthy green leaves.
•Natrassia infections, aka Arbutus canker: Spreads via spores and attacks injured tissue. It is
particularly common on trees by the ocean. Trees stressed by compaction, construction, strong
sun and bark/pruning injuries frequently get black cankers. A vigorous tree can callus over
dead tissue, but often eventually kills the whole branch or tree by girdling. Wind carries the
spores.
•Root Rot (phytophthora cactorum): Infects roots/tree trunk with cankers usually developing at
base. Appear water soaked with loss of upper foliage. Trees in poorly drained soil are most
susceptible. Spores require free water to germinate and exist in soil and diseased plant debris.
They are spread through running water/rain splash.
•Fusicoccum aesculi, aka Madrone canker: Begins at branch tips and works inward. Bark turns
dark red, then black and looks burned after the branch dies. Spores are spread by rain, wind
and possibly insects. Doesn’t attack vigorous trees.
Garry Oak
Facts
 Oaks do not require super dry rocky conditions; they just tolerate these situations better than
competing trees. They grow better in deep, rich soil and can grow up to 35m tall, but are often
short in rocky habitats.
 Garry Oak ecosystems support the highest diversity of plants in coastal BC, as well as a high
diversity of insects, reptiles, and birds. A Garry Oak does not equal a Garry Oak ecosystem.
Garry Oak ecosystems contain more species at risk of extinction than any other ecosystem in
Canada.
 Plant seedlings where they are intended to grow because they do not transplant well.
 Acorn amounts are variable from year to year, best to take advantage of good years. That
being said, there aren’t really good years on Mayne Island because most Garry Oaks on Mayne
are in dry conditions, and produce very few to no acorns. MICS is growing some and will have a
limited selection for sale in Fall 2014.
Propagation
 Best propagated by seed
 Collect acorns during late August to early November after they fall on ground; or you can hand
pick them from trees when they easily separate from their cap.
 Do a float test to see which acorns are viable; rotten ones float.
 Plant asap approximately 1-2” deep in a deep container with sandy, free draining soil. Keep the
soil moist and well aerated.
 Acorns will first put out long taproot in winter before the stem.
 Outplant in the fall following completion of a second growing season.
 Follow the same outplanting rules as an arbutus.
Diseases
 It is normal to see nibbled oak leaves/leaves with small holes in them from galls cause by native
gall wasps whose population is kept in check by native parasitoids.
 There are some introduced insect pests such as jumping gall wasps, oak leaf phylloxeran and
winter moths. These can be more problematic than native insects, but many oaks recover from
moderate infestations without treatment.
Arbutus Foliar Diseases/Leaf Insect Activity



Common, but mostly cosmetic unless repeated defoliation occurs
Affect previous growth, shed in July leaving healthy leaves
Splashing of diseased foliage & unraked, diseased leaves, can spread spores
Didymosporium arbuticola
Rhytisma arbuti
Exobasidium leaf blister
Arbutus Pathogens Likely to Cause Tree Death
Phytophthora cactorum
 Infects roots & tree trunk, cankers appear at base and appear water soaked.
 Bark is discoloured with loss of upper foliage
 Occurs on trees in poorly drained soil
 Spores require free water to germinate and exist in soil/diseased plant debris
 Spread through running water & rain splash
Arbutus Canker (Nattrassia mangiferae)
 Often develop because of bark injury
 If tree vigorous enough can callus over dead tissue
 Kills complete branches or trees by girdling
 Appears as discolouration, longitudinal cracks
 Wind carries spores
 Commonly occurs where exposed to strong sun or injured by
pruning or mechanical causes
Madrone Canker (Fusicoccum aesculi)
 Begins at branch tips, works inward
 Bark turns black and looks burned
 Spores spread by rain, wind
 Doesn’t attack vigorous trees
Native Garry Oak Galls
 Normal to see nibbled oak leaves and leaves with small holes
 Native gall wasps can cause leaf
imperfections, but native parasitoids keep
in check and they don’t pose a serious
threat
Speckled Gall Wasp Gall (Besbicus
mirabilis)
Introduced Garry Oak Insect Pests

Many Garry Oaks recover from moderate infestations without treatment
Jumping Gall Wasp (not yet seen on Mayne)
 Mustard seeds on underside of leaves
 Yellow & brown spots left where galls attached
to leaves
 Can cause minimal spotting of leaves to
premature defoliation
Oak Leaf Phylloxera
 Cause yellow spots on leaves from May to June
 Browning/defoliation in late July
 Heavily affected lose leaves, but trees produce second
set in August