Saturday, August 26, 2017

Wooly Oak Aphids

I received a call from a client who complained that their oak tree was dropping fuzzy stuff all over the area underneath its canopy. I asked them to bring it in and this is what I saw:

Leaf with cottony wax and visible aphids. 

I then put it under a magnifying scope and was able to see the culprit:

Closeup showing (l) aphid, (r) egg surrounded by waxy 'wool' produced by the aphids.

It was Wooly Oak Aphid, one of a pantheon of insect pests that attacks oaks. Like many pests on oak it is mostly not a threat, just a nuisance. Time is the usual insecticide, with infestations resolving themselves within a month or two when increasing attacks by predators and the changing physiology of the oak itself lead to its demise.

Links to more information on the Woolly Oak Aphid:

Woolly Oak Aphids - BugGuide.Net
woolly oak aphids, Stegophylla brevirostris, on black oak leaf. - YouTube
Aphids Management Guidelines--UC IPM
woolly oak aphids -Stegophylla brevirostris Quednau and Diphyllaphis microtrema Quednau
Dancing woolly aphids will probably stab you - Scientific American Blog Network

Friday, August 25, 2017

A Handful of Climate Appropriate Trees

The following trees have been picked because they are relatively climate appropriate. Keep in mind that 'climate appropriate' means more than just low water use. Many east coast and european trees require not only water but also cold winters in order to remain healthy. Also, many tropical trees are frost sensitive here and have problems with frost either killing or damaging them. To find a specimen of these trees here at the Arboretum just click on the icon for that tree in the map above. For more information on each tree just click on the link associated with its name and it will take you to the Cal Poly Selectree Database entry for that tree if it exists. 

Afrocarpus falcatus

Geijera parviflora

Melaleuca linariifolia

Lagerstroemia indica

Citrus and other Fruit Trees

Ceiba speciosa (Chorisia speciosa)

Moringa hildebrandtii

Brachychiton rupestris

Callistemon viminalis 'Red Cascade'

Eucalyptus torquata

Corymbia (Eucalyptus) citriodora

Cedrus atlantica

Draceana draco

Olea europaea ssp africanus

Sequoia sempervirens

Quercus polymorpha

Quercus  rhysophylla

Platanus mexicana

Tuesday, August 22, 2017

LAist Names Us One of the Best Places in L.A. to Watch Birds

Bluebird at the Arboretum

Popular Los Angeles blog has named the Arboretum one of the best places to watch birds. We are also listed by the Pasadena Audubon Society as one of the best places to watch birds as well.  There have been over 250 species of birds observed here, so, yes we are.

This is great news, I'm going to tweet it. 😁

Tuesday, August 15, 2017

Glassy Winged Sharpshooter

Glassy Winged Sharpshooter

I had several of these brought into my office several days ago. They are partly responsible for the demise of Oleanders all across Southern California. Their feeding activity centers around the water conducting tissue in the plant they are attacking. The orange bulb shaped area that you see on the bottom of the leafhopper in the picture is its 'head pump', a muscular organ that helps the insect pump the watery xylem fluid (mostly water coming from the roots) from the plant and through its body. 

Glassy Winged Sharpshooter
This feeding method means that it doesn't have to compete with sap sucking insects like aphids and scale, but it does require the insect to process a lot of fluid through its digestive track because xylem fluid is lean on nutrients like sugar and dissolved nitrogen compounds. This causes if to expel water out of its anus like crazy, as can be seen in this video. These insects are partly or mostly responsible for trees that 'rain' drops of fluid down around you in the summertime. 

Should you control these pests? Generally, no. However if the squirting gets to be too much you might try a pyrethrum based organic control like Pyganic, however be very selective as far as what and where you spray because this insecticide, like many pyrethrum based products, will eliminate beneficial and predatory insects as well as the pest.