pests and diseases

August – Powdery mildew, the fungus that fears water

August 23, 2012
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powdery mildew

Powdery mildew on Nandina domestica (Heavenly bamboo)

Powdery mildew is a fungus but a strange and counter-intuitive one; it hates water.

A variety of fungi can cause powdery mildew, some species will attack an array of different plants; others are host-specific. Powdery mildew likes shade and mild temperatures and it dislikes water. Leaf temps above 90°F may kill some powdery mildew. Direct sunlight can slow it down and the spores die in water. Read more »

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PLANT UPDATE – August, defoliating and sickly hawthorns (Crataegus sp.)

August 15, 2012
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Hawthorn

Hawthorn suffering from Entomosporium leafspot disease

In April I wrote about hawthorns (Crataegus sp.), the good and the bad. The photo above is an example of the bad. Really, do you want this in your yard? If you have one of these unfortunate trees, is there any reasonable thing that you can do to keep it from defoliating? Not really. Read more »

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August – Virgin Mothers, the secret world of aphids, a must-see video

August 9, 2012
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yellow aphids

From beckstei’s photostream

I have a fondness for aphids. Not exactly a fondness but certainly a respect. I don’t much like them sucking the sap of my plants but ever since I found out that they are capable of giving birth without the benefit of a male (parthenogenesis) I’ve wondered if they aren’t much further along than we, evolutionarily speaking. Babies with sex at times or without, convenient. Eric Grissell, an entomologist and gardener wrote an enchanting book on insects called Insects and Gardens. It’s educational and very readable, with lots of cool photos and fun facts that you might or might not want to know. Read more »

photo by: beckstei
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July – Oh dear, galls on the kinnikinnick

July 13, 2012
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KINNIKINNIK GALLSKinnikinnick aka Arctostaphylos uva-ursi aka bearberry is an evergreen, drought tolerant northwest native groundcover for sun. A good plant if a bit difficult to get going. In addition to that slow takeoff, kinnikinnik has one other flaw – galls. Read more »

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June – Lavender and spittlebugs

June 28, 2012
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What is it with lavender and spittlebugs? Every year as the flowerheads are forming the spittlebugs arrive. They definitely seem to prefer Lavandula angustifolia to Lavandula stoechas (the one with the bunny ears) and certainly can be found on many other plants but around here L. angustifolia seems to be their favorite haunt. Read more »

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April – Ribes sanguineum – a luscious native with a dark side

April 20, 2012
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Ribes sanguineum

Ribes sanguineum, Ballard Locks, Seattle

I have some native plants in the yard but the fact that I don’t have more leaves me with a low-grade feeling of guilt. I know they are well adapted to the climate and the animals, but frankly, quite a few are homely which tends to give the whole bunch a bad rep. In Ribes sanguineum I thought I’d found the perfect guilt-free plant, a NW native that is superbly ornamental, but of course it had to have a dark side. Read more »

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Organic pesticides, organic doesn’t mean benign

April 17, 2012
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basket of apples
abac077 / Foter

My husband brings home organic produce and eats it without washing it. I tell him that organic doesn’t mean no pesticides – they just have to be an organic ones – but he persists.

I got on this kick based on a blog post from The Garden Professors, my favorite gardening blog. A recent post addressed rotenone, a plant-derived (organic) pesticide that has been voluntarily taken off the shelves by its manufacturer. It’s particularly harmful in the aquatic environment and may cause Parkinson’s disease. Although it’s technically off the shelves it can still be bought. I found some at Amazon (Bonide Garden Dust), and who knows how many containers are hanging around in people’s garages. Read more »

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