Otiorhynchus sulcatus – black vine weevil

black vine weevil

Otiorhynchus sulcatus                   Family: Curculionidae
Common name: black vine weevil
Host plants: rhododendrons, azaleas, Kalmia, Euonymus spp., and other broad-leaved evergreens, as well as hemlock and Taxus (yew).
Adult size: about ½ inch (13 mm) long

Type: Pest

Life cycle: Generations per year: one in the Pacific Northwest
            Egg: 8 – 20 days
            Larva: 8 – 10 months
            Pupa: about 10 days
            Adult: about 6 – 7 months; some may overwinters

weevil pupa on backDescription & Life Cycle: This weevil overwinters in the soil as immature larvae. In early spring, when the larvae have reached their mature sixth instar stage at 0.4 – 0.6 inches (10 – 15 mm) long, they enter the pupating stage. They are white and have the rough outline of the adult weevil. This last roughly 10 days after which the adults emerge. This is usually from late May through June. Adult weevils require 3 – 4 weeks of active foliage feeding before they start laying eggs. As many as 500 eggs are laid in the soil around the base of host plants over a 2 – 3 week period. The legless white larvae with a brown head will hatch in 10 – 14 days and begin feeding on the plant roots. In the fall, when the temperatures start to decrease, the larvae will move deeper into the soil where they will overwinter.

Special Notes: Native to Europe, this weevil species was discovered and identified in Connecticut in 1910. Since that date, it has become widespread throughout North America.

It is interesting to note that only female adult weevils are produced in North America. They reproduce parthenogenically. Adults feed on host plant leaves during the night leaving a multitude of half-round notches along the edges of the leaves. In a particularly high weevil populated area of the garden, this can look quite unsightly on your targeted evergreen plants.

black vine weevilRemedial Action: There are some insect killing nematodes available which will control root weevils in their immature, larval stage. These are applied as a soil drench and best used when the soil temperatures are 12 °C (55 °F) or higher in late summer and early fall. Soil must be very wet at time of application and never in direct sunlight. The UV rays will quickly kill the beneficial nematodes.

Unfortunately, there is not much data on the effectiveness of this treatment.

 

Posted on May 17, 2022

Garden Tip: Adding compost the easy way

by Leslie Cox; Monday; November 29, 2021

An easy way to mix your compost into the soil is to spread it over your garden in late fall. Cover with a mulch of hay or chopped leaves and let nature take its course. Come spring, the winter weather and the soil organisms will have worked the compost in for you.

 

Garden Tip: Mulching young plants and trees

by Leslie Cox; Monday; October 25, 2021

newly planted espalier apple tree

If you have incorporated new plants in your landscape this last summer it is a good idea to cover them with mulch for protection against freezing temperatures.

The best mulch material is leaves. They are on the ground anyways, so it is easy to either rake them up and spread them over the garden beds, or run over them with the lawn mower and spread the leaf mulch over the plants.

If you do not have any deciduous trees on your property, ask or beg your friends, neighbours, family members if you can steal some of theirs.

If you do not have any access to leaves, bark is a good substitute. We prefer the fine bark mulch which is available from our local pole yard but you can also by bagged bark from your local nursery or big box store.

Straw is another good mulch option but most people prefer to use this material on their vegetable gardens rather than on their front yard garden beds. It sometimes cones down to aesthetics…and the rules in some development communities. Just be sure to buy straw and not old hay. Hay, even the old stuff, will still have viable seeds in it which you will wind up cursing next spring.

Whatever you use, spread your mulch material 4 – 6 inches (10 – 15 cm) thick over your plants. This will provide adequate protection against freezing temperatures.

One final tip…or warning…

Do not spread the mulch right up against the trunks of your trees, especially young trees, Best to leave a 6 inch (15 cm) gap around the base of the tree. Otherwise, you will be creating good camouflage for mice, squirrels and other chewing demons who like to chew on fresh tree bark.

 

Amelanchier x grandiflora ‘Princess Diana’

Amelanchier x grandiflora ‘Princess Diana’ 
(am-uh-LAN-kee-er x gran-dih-FLOR-ah)
Syn. Amelanchier laevis ‘Princess Diana’; Amelanchier ‘Princess Diana’
Family: Rosaceae

Common name: apple serviceberry; hybrid serviceberry; seviceberry
Zone: 4 – 9
Height: 15 ft (4.5 m)   Spread: 12-15 ft (3.6-4.5 m)
Aspect: full sun; partial shade
Soil: moist; acidic; well-draining
Water: regular     

Description: Reasonably small, deciduous, understory tree with finely-toothed, 3 inch (7.6 cm) long, oval-lanceolate leaves, emerging with bronze tints in spring, gradually changing to dark green though summer before changing a brilliant red to orange-red in fall. Showy white flowers appear in April followed by edible 3/8-inch (9.5 mm) diameter edible berries which are a deep red-purple when fully ripe in late June through early July.

 

Special Notes: Amelanchier spp. are native to North America. Amelanchier x grandiflora is a hybrid cross between A. arborea (downy serviceberry) and A. laevis (Allegheny serviceberry), two species of North American serviceberries.

‘Princess Diana’, one of several named cultivars in this Amelanchier species, is known for its abundant floral display of white flowers, wide canopy and its vibrant fall colour. It was discovered in the mid-1980s in a garden in Elm Grove, Wisconsin. A U.S. Plant Patent PP6,041 was issued on October 20, 1987.

 

Pests and Diseases: There are no serious insect or disease problems, although amelanchiers can occasionally have problems with powdery mildew, leaf spot, rust, fire blight and canker. So far, our tree has not experienced any problems whatsoever. (Touch wood.)

 

In our Zone 7a garden: We absolutely adore this small tree in the back garden! It resides in the shadow of the ancient transparent apple tree and is further shaded by the 12 ft (3.6 m) tall cedar hedge. Still, the flowers appear in April and there always seems to be enough bees around at that time to perform their pollinating duties.

I keep a close watch on the berries when they start to come as I like to pick them for my Serviceberry Cobbler. (Click here for the recipe.) I have to be quick because the birds love these berries too, especially the cedar waxwings who make a point of arriving in our garden to feast on the serviceberries. Often, I am picking berries from the lower branches while several cedar waxwings are enjoying them above my head.

While I have yet to make jam or jelly from serviceberries, it is reported to be quite good. Perhaps I will attempt these preserves next season as we do love our Aronia Berry Jelly and Oregon Grape Jelly.

One good piece of information to note: serviceberries can be picked before they are fully ripe as they will finish ripening if laid out in newspaper-lined beer flats.


Royal Horticultural Society’s Award of Garden Merit 2012

 

Posted on October 20, 2021

 

 

Garden Tip: Rescue drowning plants

by Leslie Cox; Monday; October 18, 2021

Saxifraga fortunei 'Magenta'Be sure to check your potted plants after a heavy rainfall. Plants…any species that are not marginal (ie. those that prefer a spot by a pond or stream)…can develop crown rot if they are wallowing in a puddle of water in their pot.

Here in the Pacific Northwest, crown rot is one of the main causes of plant deaths through the fall and winter seasons. (Sadly, we lost this beautiful saxifraga to crown rot two years ago.)

Take away the trays under the pots to allow for free drainage. Or, if there are no trays underneath but the plant is still water-logged, place a couple of wood blocks or flat rocks underneath the pot to raise it up off the ground. If the plant is still swimming in water, knock it out of the pot, check the drainage hole is not plugged and re-pot the plant with up to one-third sand or small grit added to the new soil mix to increase the drainage.

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