Tuesday, June 25, 2013

Polyphagous Shothole Borer Susceptible Tree Variety Numbers Growing.

I've been accused of being alarmist about the potential of the Polyphagous Shothole Borer to be a destructive pest here, but it's been pretty alarming. A new paper by Dr. Akif Eskalen and several other researchers has come out detailing the growing number of hosts and trees affected by this pest doesn't do much help. Turns out of all the most planted ornamental trees here in Southern California, over 60% are attacked by the beetle in some way.
Senna tree showing oozing from Polyphagous Shothole Borer  attacks. 

Tuesday, June 11, 2013

Pretty Looking Leaf Spot on an Ornamental Pear

A local arborist brought this in over the weekend -its Entomosporium leaf spot on an ornamental pear (probably a Bradford pear). It will not kill the tree but if you don't attempt to control it the tree may become weakened from defoliation. The treatment likes in changing the cultural conditions so that the inevitable coating of fine mist that is deposited when our 'June Gloom' overcast layer is really deep and gloomy dries out as quickly as possible, giving the fungi's spores less of a chance to germinate. Besides removing all the infected leaves and disposing of them in the trash (composting them could recycle the spores) this can be achieved by opening up the tree near the base using selective pruning, removing organic  mulches under the canopy of the tree (they keep the moisture levels up too high) and making sure irrigation water isn't hitting the leaves or trunk of the tree. If infestations of Entomosporium are high it's not a bad idea to apply a copper fungicide until the weather gets drier. 
Entomosporium leaf spot on ornamental pear.