Wednesday, July 10, 2013

Lessons Learned from the Wilsonville Bee Kill


Before I saw it with my own eyes, I wouldn’t have believed that 50,000 bumble bees forage in the trees of a suburban big box store parking lot. They do. We know that now, because at least that many died in the Wilsonville, Oregon Target parking lot in a single week in late June. 

This picture was taken on June 17th, two days after the trees were sprayed for aphids with a product called Safari. Each black dot on the pavement is a dead bumble bee, almost all of them Bombus vosnesenkii.
Picking up dead bumble bees.

The pattern was the same under each of 55 European linden trees (Tilia cordata), and the bees kept dying for a week until the City of Wilsonville led a heroic effort to cover each tree with shade cloth. Though this isn’t a traditional invasive species story, it contains lessons for invasive species warriors. 

Lesson 1: Oregon’s wild bee populations are healthy. There are a couple of known exceptions, but in general, we can be thankful that our native bees are thriving. This is important because wild bees pollinate many of our native plants and agricultural crops. Honeybees get all the credit, but native bees do much of the work. On a larger scale, healthy pollinators indicate healthy habitats; we’re lucky in Oregon to have an environment that is in pretty good shape – and worth protecting.
Lesson 2: Pesticides are powerful tools. Used correctly, they are often our most effective tools for early detection and rapid response programs (EDRR) programs.  Most eradication programs depend on them. However, they can occasionally cause problems. We need to learn from these instances to prevent them from happening again.

Lesson 3: Pesticide experts commonly refer to, “The label is the law.” That is true, but labels and laws are sometimes flawed and often open to interpretation. It could be months before the official investigation of this incident is complete and the Oregon Department of Agriculture (ODA) determines whether there was a violation. Given this parking lot site, how would you interpret the Safari label language? “Do not apply this product or allow it to drift to blooming crops or weeds if bees are visiting the treatment area.” A supplemental label adds: “For trees in forests that are pollinated by bees or other invertebrates, make applications post-bloom.”

Lesson 4: Linden nectar by itself can be toxic to bees!* Dead bumble bees are not uncommon under unsprayed linden trees. The publicity generated by the Wilsonville bee kill resulted in many more reports of dead bees. Most of them turned out to be relatively small numbers probably not related to pesticides. So far, we’ve only found one other tree in Hillsboro that was associated with dead bee numbers similar to those in Wilsonville. That tree had been sprayed with the same pesticide last March. Other linden trees along the same street receiving the same treatment didn’t have any dead bees. That will be a puzzle for the investigators!

Interestingly, honey bees weren’t affected to the same extent as bumble bees.  The honey bees were foraging on the linden flowers, but few were dying. One reason might be that honey bees are from Europe; they evolved with European linden nectar.  We’ll have to wait for the investigators and scientists to sort out whether toxic nectar played a part in this incident.

Placing netting over blooming linden trees.

Lesson 5: When people work together, they can do amazing things. On Thursday, June 20, ODA hosted a conference call bringing together officials from the City of Wilsonville, entomologists from ODA, Xerces Society, and Oregon State University, and other interested parties. We discussed how to stop the bee kill as well as a long list of less palatable options, from cutting the trees down to spraying the trees with garlic-based insect repellent. The only option that seemed to have promise was to cover the trees with bee-proof netting, and it wasn’t at all clear how to do that. City of Wilsonville staff figured it out by the end of the day. The very next day, 60 people and six bucket trucks representing eight agencies/organizations went to work. Crews stapled panels of shade cloth together, passed 40’ X 40’ sheets to bucket truck crews, and with much tugging and adjusting, the netting was draped over the 25’ tall trees. At 5:10 PM, the last net was tied off at the trunk, and the Wilsonville bee kill was over.

It was a day I’ll never forget, and none of us should ever forget the lessons we learned. 

Dan Hilburn 

*Pawlikowski,T. 2010.  Pollination activity of bees (Apoidea: Apiformes) visiting flowers of Tilia cordata Mill. And Tilia tomentosa Moench in an urban environment. J. Apicultural Sci. 54(2): 73-79.

Saturday, June 1, 2013

What to do with Western Juniper?

Juniper encroaching on sage brush habitat in Oregon.
         Not all invaders are aliens. Western juniper, Juniperus occidentalis, is invading grassland habitats in central and eastern Oregon. This native species doesn’t fit our official definition of an invasive species—“nonnative organisms that cause economic or environmental harm” (ORS 570.755) —but it is sure acting like one.

         Between 1936 and 1988, the area of juniper forest in eastern Oregon increased 5.3 times from 420,000 to 2,200,000 acres.* The reason for this slow but steady invasion is that we’ve changed the way grasslands are managed. Native Americans used to set fire to the grasslands to keep them open. Not any more. We do our best to suppress fires because they threaten houses, livestock, and other things we care about.

         Unfortunately, we’ve created a juniper invasion. Encroaching juniper is degrading sage grouse and other wildlife habitat, shading out native grasses, sucking up ground water, and creating opportunities for invasions of weeds and other undesirable species. The state has convened a large task force to look for solutions. It’s called the Western Juniper Working Group (WJUG), and I’m the representative from the Oregon Department of Agriculture (ODA).

         I’m learning fast that it is complex issue. Some people on the WJUG would like ODA to declare Western juniper a noxious weed. We’re not going to do that. It is a native species, and thus has a place in Oregon ecosystems. However, the expansion of juniper is a problem, and if some sort of official recognition would help focus attention on it, we should consider our options. I’m looking forward to the discussion at the next State Weed Board meeting.

         Reintroducing fire as a management tool would seem to be a no-brainer, but there are serious liability questions. Currently, if your controlled burn gets out of control, you’re liable for fire suppression costs and damages.

         Most juniper suppression projects today are cut, pile, and burn. It is laborious, costly, and not popular with some members of the public.

         The ideal solution would be to find economic uses for juniper so there would be an incentive to log the trees. There are two challenges to that idea. One is that junipers occur in areas where there aren’t many mills and markets. Thus, costs to transport harvested wood to places where it can be processed are generally prohibitive. Secondly, compared to other trees in Oregon, junipers are short and gnarly. Juniper just doesn’t compete with Douglas fir, Ponderosa pine, and other conifers in terms of producing a suite of desirable wood products.

         Juniper does make interesting rustic furniture, but it’s a niche market. You’ll find it at a gallery in Sisters, Oregon, but not at J.C. Penny. I have a coffee table with twisted juniper legs that I like, but it’s not for everyone.

         Juniper is superior to all other woods in one way. It makes great fence posts that don’t rot. OSU has fence post trials that go back to the 20s and 30s. The juniper heartwood fence posts from way back then are still standing! I’ve never seen juniper posts for sale in the building supply stores I frequent, but that is probably because no one asks for it, and it would be more expensive. Maybe we can start a movement to encourage people to ask for local juniper instead of using treated wood posts and landscape timbers. I’d pay more if I knew it was good for the environment and would last longer, wouldn’t you?

         We need a good slogan. How about:
  • Got juniper?
  • Juniper, the other fence post.
  • Fence the invader! 

Help me out here. What would you recommend?

Dan Hilburn

*Gedney, D.R., D.L. Azuma, C.L. Bolsinger, and N. McKay. 1999. Western Juniper in      Eastern Oregon. USDA, Forest Service, Gen. Tech. Report PNW-GTR-464.     53pp.

Saturday, May 4, 2013

Where do You Buy Plants?


         I’m a recreational vegetable gardener and semi-successful practitioner of low maintenance landscaping. My wife likes flowers. Every spring when the weather warms up, we drive to our favorite nurseries and stock up on seeds, plants, bushes, and trees. We’re lucky to live in western Oregon. Most of Oregon’s 3,000-plus nurseries are within 50 miles of our home. If you’re like us, you probably feel good about buying local plants.

         But are those plants in the garden center really local? You’d be surprised at the amount of plant material Oregon imports, some of it from overseas. Below is a summary of the nursery stock imported into Oregon from foreign sources last month (April, 2013).

12
Drosera
Australia
400
Origanum s
Israel
227
Sarracenia
Australia
100
Pelargonium
Israel
4,650
Dioneae
Australia
200
Rosmarinus officinalis
Israel
6,900
Cotinus
Netherlands
600
Salvia
Israel
700
Cordyline
Singapore
200
Satureja
Israel
8,000
Dracaena
Singapore
100
Stevia
Israel
3,210
Paeonia
Canada
1,000
Thymus
Israel
10,000
Brunnera
New Zealand
200
Zaluzianskya
Israel
1,500
Calibrachoa
Israel
26
Iris
Australia
360
Impatiens
Israel
77
Iris
Thailand
120
Nemesa
Israel
31,500
Ranunculus
France
920
Petunia
Israel
10
Plumeria
Thailand
1,400
Calibrachoa
Israel
38
Iris
Australia
400
Artemisa
Israel
1,800
Calibrachoa
Israel
200
Lippia
Israel
3,500
Petunia
Israel
1,000
Menta
Israel
1,000
Petunia
Israel
200
Ocimum
Israel
800
Petunia
Israel
2,000
Sedum
Israel
600
Petunia
Israel
3,600
Impatiens
Israel
1,400
Nemesia
Israel
2,000
Nasturtium
Israel
500
Ajuga
Israel
4,100
Erodium
Israel
900
Begonia
Israel
100
Petunia
Israel
1,300
Calibrachoa
Israel
1,000
Verbena
Israel
3,900
Lantana
Israel
700
Lantana
Israel
3,400
Petunia
Israel
600
Verbena
Israel
400
Calibrachoa
Israel
1,600
Lantana
Israel
800
Calibrachoa
Israel
100
Lantana
Israel
800
Petunia
Israel
200
Verbena
Israel
1,200
Petunia
Israel
100
Calibrachoa
Israel
100
Petunia
Israel
300
Verbena
Israel
105 g
Abies seed
Denmark


         Readers with a botany background will notice many common flowers and herbs on the list. Note that this is just the plant material imported from outside the country. Much more comes in from other states.

         Some of what is imported is new varieties developed elsewhere and not yet available here, but looking at the numbers above it seems some nurseries are outsourcing their propagation. It boggles my mind to think that Petunias grown in Israel can be shipped to Oregon more cheaply than they can be produced here!

         Leaving behind the incomprehensible economics, let’s turn to the plant pest risks. All the countries above have plant pests and diseases not present in Oregon. Commercial shipments like these are certified in their country of origin and screened when they enter this country. At the plant inspection stations (the closest one to Oregon is Seattle), a percentage of the boxes are opened and the plants are inspected for pests and disease. If there is a heavy infestation of a blight or pest of concern, the shipment is rejected.

         More likely though, a plant here and there will have a few whitefly eggs or a root rot, and the inspector doesn’t have a chance of spotting all the potential problems. Some will get through, and a percentage of those will find Oregon’s climate to their liking.

         When looking at invasive species pathways, global trade and travel in plant material is riskier than trade in manufactured goods. A live plant is the perfect vehicle for a hitchhiking mealybug or fungal blight, only it’s more than a ride. It’s a hop, skip, and a jump - from one continent to another.

         This is an example of how we’re our own worse enemy when it comes to invasive species. It is a people-created problem. We bring them to Oregon. On the positive side, that means that people are also the solution. I don’t blame nurseries for shopping around for the best prices from potential suppliers, but I do think the price of flower starts from overseas should include the cost of dealing with the invasive species problems they inevitably bring.

Dan Hilburn