Thursday, August 1, 2013

Bugs and Fungus Come Into My Office


These were brought in by a woman who was worried about mushrooms poisoning her dog. Previously she had brought in some Conocybe mushrooms that were poisonous but may or may not have been responsible for her dog getting sick (they are known to contain toxins like the ones in the 'Death Cap' mushrooms but the chemistry of the ones in the Conocybe is such that they have to be absorbed directly into the bloodstream to be harmfull). These turned out to be Collybia fuscopurperea (also called Gymnopis villosypes) an indedible but not known to be poisonous mushroom that is classed by many as a 'LBM' (a 'little brown mushroom' so minute and inedible that its toxicity is inconsequential),

Collybia fuscopurperea

A Beetle Responsible for the Death of An Oak Tree?

 The below beetle and larvae was brought into my office to find out if it was the cause of death of live oak (Quercus agrifolia) here in Arcadia. Turns out this little bugger, called a Nautical borer, chows down on dying and dead oaks but is not responsible for the initial demise of the tree.

Nautical beetle.

Nautical beetle larvae
 What is most probably the cause of the trees demise was evidenced by signs of another, more insidious beetle on an oak tree located nearby. Both branches and trunk of the tree showed the exudate and white sawdust halo of the Polyphagous Shot Hole Borer (PSHB), a fairly new pest that is decimating trees in the area. 
Oak tree branch showing the soaking spot with small sawdust halo inside that is the hallmark of the Polyphagous Shot Hole Borer(PSHB). 

Soaking area on oak tree -a sign of PSHB. 
More on the Nautical borer can be found here: A Field Guide to Insects and Diseases of California Oaks
More on the Polyphagous Shot Hole Borer can be found here:

Sunflower Leaf Problems

I got the below sunflower leaf from a patron who was worried about weather these symptoms were a death sentence for the sunflower they were found on. This is the sunflower leaf miner, and like most leaf-miners it can be controlled by removing the infested leaves from the plant and cleaning the fallen ones out from underneath the plant. Chemical control is really not necessary unless you are entering the entire plant in a contest and the prize is over $10,000. One good way of keeping damage levels down (besides the above) is to keep fertilization to a minimum. High levels of nitrogen not only make the leaf soft and easy to feed on, but directly feed the leaf-miner with a nutrient that lack of otherwise limits its growth and reproduction. 
Sunflower leaf miner
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