Disasters just seem to happen.  Yesterday I got one of those calls. Confirmed Phytophthora! Most crops are listed on a protective, or curative, plant protection product, (read pesticide label). Control and or disease prevention should be relatively easy, and we all know about cultural controls; being clean; few, if any visitors walking about the greenhouse or field; all those sorts of things. So how does it happen? This pathogen is so destructive and contagious, thatusually once it is recognized it's over, off to the dump infected plants go. 

And then we complicate the system. Let's try eatable and organic. Organic is in demand and may even pay-off better, compared to conventionally grown. That was the call yesterday. What to do? First, all the plants get tossed. Then the greenhouse was cleaned. But with organic we are limited on how things are cleaned too! After elbow-grease we will add Oxidate to the water, the organic version of Zero-Tol. And then we will use Oxidate continually for a while, in hopes the pathogen is controlled. Time will tell.

Earthquakes, weather, fires, pests, and pathogens are common enough. Then add the man-made disasters to the mix. Large companies going bankrupt send economic ripple effects and generate questions and wonder amongst us all. I think growing organically is possible.  I think growing in general is possible. I know surviving is possible, even if we trash the old and bring on the new (perhaps better protected this time).  Pest Control Advisors can help with the plant growing and protecting.

It is good to not be in the insurance business, because disasters just seem to happen. I am grateful to be in the business of helping growers grow. That is what PCAs do...

Ambrosia Beetles

I just received a notice of Q and A rated pests in CA for the last week in April and found an interesting note on a recent infestation of ambrosia beetles in northern CA. I thought it would be a good time to educate you on these little beetles. Without giving too many details, a customer from another state complained about live beetles in their delivery of wood product (not ornamental) from a CA company and samples were sent to the California Department of Food and Agriculture (CDFA) Plant Pest Diagnostics Laboratory in Sacramento for identification. Live adult beetles were found infesting the wood, and was identified as Xylosandrus crassiusculus, a common ambrosia beetle called the granulate ambrosia beetle or the Asian ambrosia beetle. Cal-Fire confirmed to CDFA that the infested wood sample was destroyed. In response, the CDFA notified the County Agricultural Commissioner's Office of the find, and they are performing a follow-up inspections.

Ambrosia beetles are a group of beetles in the bark beetle family, Scolytidae. However, there is some argument by taxonomists that the group actually belongs to the Family: Curculionidae (weevils and snout beetles) as a subgroup Scolytinae. That's for the taxonomist to argue about. I have no problem concentrating on the pest status of the beetles. They can have profound effects on plants, mostly tree species, by feeding on the cambium layer or sapwood. They tend to attack smaller branches in the upper crowns of trees, but have also been found on the main stems of apparently healthy large trees. A characteristic indicator of an infestation is the presence of small toothpick like structures, which are frass or excreta of feeding beetles being pushed out of feeding galleries. The toothpicks radiate from the trunks and branches of infested trees. If the inside of the trunk is dissected, it usually reveals galleries and staining caused the symbiotic fungus. You can see some great photos of the Redbay ambrosia beetle, the damage, and the toothpicks at the following web site: http://cisr.ucr.edu/redbay_ambrosia_beetle_laurel_wilt.html.

Ambrosia beetles are small (2mm) and usually associated with fungi, and usually only one species of fungi. The beetles don't really eat wood, but instead excavate tunnels in trees in which they cultivate the fungi as food. The fungi stain the wood blue, black, or dark brown. The fungal spores are carried from tree to tree on the adult beetle's exoskeleton near the mouthparts, which makes sense since they were associated with a fungal infection caused by their parents during development to the adult stage. Once galleries are started and spores released, the spores penetrate and destroy the plants vascular system. If enough of them circle the tree, some of these fungal gardens can girdle and kill the tree. The best-known example of this at the moment is the Redbay ambrosia beetle, Xyleborus glabratus, which causes laurel wilt.

The Redbay ambrosia beetle is native to the Far East, but it was introduced into Georgia in 2002 possibly by infested packing materials, such as wooden crates and pallets. The beetle now infests Florida where the beetle and its associated fungus have caused substantial destruction to the native Redbay (Persea borbonia). Unfortunately, avocado is a relative of the Redbay, and avocado tree deaths are now common in Florida. If this bug gets here, the already threatened avocado industry will have another serious pest to deal with.

Ambrosia beetles are very common in CA and regularly infest deciduous fruit trees, landscape trees and oak and pine forests. Some of the more common pest species include: Striped Ambrosia Beetle, Trypodendron lineatum (Olivier), Western Hemlock Wood Stainer, Gnathotrichus sulcatus (LeConte), the Lesser Shothole Borer, Xyleborus saxeseni (Ratzeburg), redshouldered shothole borer, Xylobiops basilaris (Say), and Wilson's Wideheaded Ambrosia Beetle, Platypus wilsoni (Swaine). If SOD wasn't enough, our oak forests are constantly attacked by oak associated ambrosia beetles. The more common oak associated ambrosia beetles include the Large California Oak Ambrosia Beetle, Monarthrum scutellare (LeConte) (= Pterocyclon), Xyleborinus saxeseni (Ratzeburg), Pseudopityophthorus pubipennis (LeConte), M. dentigerum (LeConte), Scobicia declivis (LeConte), Xyleborus californicus (Wood), and Gnathotrichus pilosus (LeConte). Most of these species are sapwood-colonizing ambrosia beetles that are typically associated with recently killed hardwoods. Three of these ambrosia beetles are endemic, and both X. saxeseni and X. californicus are Asian introductions. The oak bark beetle, P. pubipennis, feeds primarily in dead oaks. For more information on oak associated ambrosia beetles, wee the following web site: www.fs.fed.us/psw/publications/documents/psw_gtr214/psw_gtr214_173-175_mcpherson.pdf.

Here locally, I have seen dracaena stock (see photo) that was infested with ambrosia beetles.    

This is not an uncommon occurrence. There have been reports of ambrosia beetles infesting dracaena for 50 years. It is usually a localized occurrence, which means not every shipment or every stalk is infested. Infestations on shipments tend to be spotty and easily dealt with. However, these infestations should be taken seriously, and infested stock should be bagged and destroyed so that they do not persist. Pesticide treatments with pyrethroids can be effective as a preventative against adults, but once inside the plant, they are very difficult to control. The biology and control of granulate ambrosia beetles can be found at the following web sites:

http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note111/note111.html, andhttp://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7421.html

 Ambrosia beetles are very common in CA and can infest just about every tree you can think of. They are a big part of the decomposition of forests, but they can be serious pests, especially when they are introduced as an invasive species. Keep you eye out for the toothpicks on tree trunks. The next time you see them, you will know more about what causes them than just about anybody.

James A. Bethke

UC Cooperative Extension San Diego

jabethke@ucdavis.edu  

760 752-4715

San Diego County Sheriff's Department
Agriculture Related Crimes from
April 15^th through May 16^th, 2011   

Crime Prevention Tips of the Month:

·         Report crimes or suspicious activity immediately to the Sheriff's     Dispatch             

·         Reassess strength of hardware such as fencing, locks, and storage   containers for security                              

·         Screen all employees-take photos of them-and verify identification

June 23, 2011 ABC's of Fertilizer and Irrigation Management in Spanish.

Colorama Wholesale Nursery,1025 N. Todd Ave, Azusa CA

8:00 am - 3:00 pm For registration and more information  

click here