Sunday, April 26, 2009

The Rusty Blackhaw

The rusty blackhaw bloomed today
Just prior to the month of May
Five stamens nigh five petals rose
Of panicles in white array

The leaves are velvet green beneath
Un-rusted and uneaten yet
Above a longhorn beetle feeds
On pollen covering up its head

The oaks nearby have fully leafed
Though flaccid and lethargic still
With yellow tinting everywhere
Awash in springtime chlorophyll

Saturday, April 18, 2009

Knowledge and Polestars

In Josephine Johnson’s Pulitzer-winning novel, Now in November, Grant and Marget come across a snake while walking on the farm. Grant can tell that it’s about to shed its skin. Marget then wishes she knew as many things about the world as Grant does. Then Grant makes a remarkable admission. “I have a fool hopeful belief,” he says, “that the more we know, the more we can come to understand.”

For those of us who are hopelessly addicted to learning new things, these are assuring words. In fact we know intuitively that they are true. Those moments in our lives when the light of understanding breaks through our otherwise clouded existence, it often comes piggy-back on what we already know – in contingencies of previously known facts.

And yet the opposite also seems true. Sometimes the more we know, the more confusing things become. In a recent evaluation of how little we know about nitrogen fixation in plants, G.J. Leigh laments that, “the more we know, the less we understand.” (See The World’s Greatest Fix, A History of Nitrogen and Agriculture, Oxford University Press, 2004, p. 178.)

This, of course, is a common theme in science and is more often expressed as, “the more we know, the more we realize that we don’t know.” This has become an aphorism and a call to humility among scientists for a long time, but scientists don’t normally understand it to mean that the more we know, the less we wisdom we have. On the contrary, most scientists believe that the more we are aware of our knowledge gaps, the greater is our understanding, at least to a degree.

So all of this seems to imply that both statements are true. The more we know, the more we do understand - in an absolute sense (our total amount of knowledge does increase). But it is also true that the more we know, the awareness of our ignorance also increases, such that the proportion of our knowledge, compared to all there really is to be known, becomes less. At least it appears less to us.

In Grant’s conversation with Marget, it is apparent that he wants understanding most of all. Knowledge is just a way of getting understanding. This is certainly a commendable use of knowledge. Many have been the abuses of knowledge for less worthy ends - such as power, prestige, or wealth. But understanding by itself is not free of ambiguity. This is because understanding implies a world view.

Knowledge without a polestar is like plowing a field without your eyes fixed on an immoveable object. You begin to wander in many different directions. The wandering may be subtle or not so subtle, but it is wandering nonetheless. This sounds a bit too subjective for most people - who want absolute facts free of value judgments or preconceived theories. The only problem with this kind of thinking is that we humans aren’t made to see the world this way. The need for a polestar is part of our nature.

Grant’s next question could easily be, “why do snakes shed their skin?” followed ultimately by, “why are there even snakes at all?” the answers to these questions can be very different if one’s polestar sees the creation as a product of chance or part of an intended order.

All of our knowledge, ultimately, is informed by our views, whether we realize it or not. Even the certain laws of mathematics will be pointed in different directions in persons of different polestars. They may be grounded immovably in fact, but the direction they are headed makes all the difference in the world.

The remarkable truth to be gained from all of this is that there is only one ordered universe that accounts for all knowledge – and therefore only one polestar that aligns with all of this knowledge. All other polestars will never be able to account for everything – there are simply too many contradictions.

Think of a million ropes (representing a million bits of knowledge) all tied to the ground and measured precisely to hold a giant hot air balloon high above the earth. When working as they were designed to, each rope is securely fastened to the balloon and carries an equal share of the weight. Any other balloon anywhere else in the world would leave many ropes unused, or twisted and out of proportion. Our balloon – that is, our world – is clearly not this way. It is an ordered world.

Instead of a twisted laws, or no apparent laws at all, we experience systems that work with great precision together in ways to foster life. Many of these systems – in fact most of them – we are ignorant of. There is a lot of knowledge that we will never have. We can therefore be forgiven for this ignorance, at least in part. Our choice of polestars, however, is a different thing. Our understanding depends on which one we chose. It seems obvious that we should choose one that is ordered the best. To me it seems obvious that this is a created order.

Saturday, April 11, 2009

King's River

This is the best time of the year to visit the foothills of the western Sierra Nevada. Lupines – colored lavender, white, blue, and violet – are covering the hillsides. The grass is actually green and the new oak leaves are small and shiny. Most of the trees have leafed out already or are bursting their buds. Scattered amid the sea of green are a few exceptions clustered in pockets of brilliant magenta. These are the flowers of the western redbud that hold back their leaves until the flowers have had their several days of glory.

We decided to spend a couple of days over Spring Break on the King’s River in the foothills of southern Fresno County, just north of King’s Canyon National Park. We camped at Kirch Flat just upriver from Pine Flat Reservoir.

King’s River is a swift yet fairly flat river. Its banks are sandy and lined with cobbles that have long endured the grinding pressure of the white-water current. There are California sycamores and lupines as big as sagebrush along the shore. A little further upriver the hillsides are covered with California poppies and a host of other wildflowers.

We found a large population of blister beetles (of the genus Lytta) feeding on the poppy petals. They were about half an inch long and were brightly metallic. Some individuals were coppery green while others were blue or just plain green. The young larvae of these beetles (called triungulins) are highly active and are known to jump from flowers onto solitary bees that come to feed. After hitching a ride to their nests, the immature beetles feed on the developing larval bees and grow fat in their underground nests. Once the bee larvae are consumed, the beetle parasitoids pupate in the soil and emerge as adult blister beetles ready for a new generation.

But this doesn’t explain the penchant that these particular beetles have for poppy flowers. It is more than likely that they are acquiring alkaloids or glycosides (both known to occur in California poppies) to protect themselves from predators. They certainly do like the flowers. We found several of them nearly skeletonized, while hanging behind the beetles, like drag lines, were strings of scarlet frass.

We also found a few scorpion flies (Bittacus chlorostigma, also known as the green stigma hangingfly) in the tall grass of the cooler shaded areas. They are similar to the crane flies that are numerous right now and, as a result, we almost overlooked them. One mating pair, however, was oblivious to our presence and let us get close enough to see their pointed mouthparts. They were locked in copula and a plant bug was clasped in their tarsi – apparently a nuptial gift for the female. The delicate yellow patch at the end of the wings matched their yellow legs and is the diagnostic character of this beautiful insect.

But perhaps our most interesting finds were near the river under driftwood. We came across a darkling beetle just under an inch long looking very much like an iron-clad beetle. These beetles are known to be very hard to smash (one has to wonder who first figured this interesting fact out). Their hard exoskeleton can sometimes be stepped-on without breaking. The insect we found was not actually one of these but a related species, Nyctoporis carinata. It is a dull blackish gray and has an intricate sculptured pattern on its back with ridges and grooves that even extend on to its head. It looks a bit like a small tank. Even its antennae look reinforced and armored.

Another interesting beetle under the driftwood was a snail-eating ground beetle (of the genus Scaphinotus, sensu lato). These remarkable insects have elongated mouthparts that they use to eat snails. The wing covers of this particular species were nearly round.

I should mention another curious incident that happened during our trip. Our campsite was spotted with the mounds of the valley pocket gopher (Thomomys bottae). There were piles of moist soil from their recently excavated tunnels and piles of drier soil from older ones. We didn’t think much of them until our dog (a poodle terrier mix) found one outside its tunnel just before sunset. The dog had probably never seen so many wild things in its life before (we were caring for it for a friend who, we expect, had not taken it out much) and so was a bit unsure of itself at times. The gopher, finding itself cornered by the dog, tried to dig a tunnel as fast as it could. Unfortunately it wasn’t fast enough and was forced to confront the small dog (looming as a giant to the poor rodent). It backed into its partially dug hole, confronted the dog and bared its re-curved teeth. If it made a sound I couldn’t hear it. Instead it tried to look as intimidating as it could. I was surprised at how long it managed to bluff the much bigger animal. It wasn’t until it tried to run for cover that the dog quickly grabbed it and then, just as quickly, drop it again. It didn’t have the nerve to finish it off. The gopher, however, had lost the use of one of its front paws and was otherwise unable to move. The dog, deciding either that the furry creature didn’t taste good or that it wasn’t worth the trouble, left the small creature to fend for itself. Knowing that it didn’t have much chance on its own, I put the poor creature out of its misery.

Overhead, the acorn woodpeckers were busy chasing each other from tree to tree and hardly noticed. A pair of kingbirds was perched on a bare branch near the river with their backs to us. They couldn’t have cared less at what we were doing. They were just gloating over the finches that they had scared away – and, no doubt, enjoying the sounding riffles of the river.

Saturday, April 4, 2009

The Asian Citrus Psyllid in California

In May of last year, a small insect about the size of an aphid – but looking more like a miniature cicada – was discovered in California near San Diego. Known as the Asian citrus psyllid, this small creature has caused a large amount of concern.

The reason is that the psyllid is known to carry a disease that is devastating to citrus trees. In Florida, the disease (known as citrus greening) is killing so many trees that some people are predicting the end of the state’s citrus industry within 15 years.

Fortunately for Californians, the disease hasn’t been detected here yet even though the disease’s vector – the psyllid - has. Even so, we’re not taking any chances. In fact, earlier this week, a room full of entomologists and other interested parties met for a full day near Sea World to discuss the issue.

For a day-length symposium, it was surprising how well attended every talk was – even the last ones. It was also surprising how engaged everybody seemed to be throughout. A big feature of the morning session was the presence of scientists from Florida discussing what had been happening in their state – including what successes they had had; and, more importantly, what had not worked well.

Florida’s number one lesson for Californians is that waiting to control the insect (and hoping that the disease doesn’t show up) is a very bad idea. The reason for this is that the disease can remain dormant in trees for over a year. Florida learned this lesson the hard way. The psyllid showed up in 1998 and a bit later the disease was detected. Efforts were made to control the insect but the focus was on those areas were the disease was apparent. As a result an ever-increasing number of trees, infected with the dormant disease, went undetected. Almost over-night, it seemed, when these trees started showing symptoms, it was discovered that much of the state was infected. Not enough attention had been given to the insects.

The bad news for California is that this lesson is more easily understood than acted upon. The psyllids are too mobile and are quite good at remaining undetected. The California Department of Food and Agriculture (CDFA) has acted promptly in putting together a team to deal with this problem, and significant efforts are being made to discover the insects and kill them, but there are two major reasons that their efforts will probably not be successful at completely containing the insect.

The biggest problem is that the psyllid has not only been feeding on citrus trees in San Diego County but it has also been feeding south of the border. In fact there have been many times more captures of the insect in Mexico than there have been in California. We can continue to kill every insect we find but unless something is done to control the pests outside our jurisdiction, our efforts will be no more effective than a fly swatter is for killing mosquitoes in a swamp.

The other major problem is that there are just too many citrus trees in California, and many of them will probably not be sampled or effectively treated no matter how much money we throw at the problem. If we only had to worry about citrus orchards, we might have a chance. It is known that the psyllids prefer feeding on new leaves from trees on the borders of orchards. It is conceivably possible to monitor these places and either treat them with effective insecticides, or else remove the trees so they can’t be reservoirs of the disease. Unfortunately, there are just too many trees in urban areas and even in rural areas outside of orchards. It isn’t possible to find all of these trees even if we had the resources.

In the last several months, despite our significant effort, the psyllid has moved from San Diego County to Imperial County, and it is now in Riverside County too. It seems to be only a matter of time before it jumps over the Transverse Ranges (or skirts them from the east) and enters the Central Valley. We seem to be pretty good at monitoring the critters, but this isn’t enough. We’re just watching them expand their range.

And then there remains the big unknown threat of a yellowing disease on tomatoes and potatoes. A graduate student has recently shown that the bacterium causing this disease is closely related to citrus greening. The bad news is that it can also infect citrus trees. It seems that it isn’t happening very often because the insect that feeds on tomatoes and potatoes doesn’t like to feed on citrus too (thus transferring the disease). The big unknown is whether or not our newly-arrived psyllid – the Asian citrus psyllid - might do a much better job at carrying it around. We might end up with an entirely different citrus greening (or yellowing) disease on our hands.

So what are citrus growers to do? Watch and despair – and pray that the disease doesn’t show up? Well, things probably aren’t that bad yet – although a bit of prayer might not hurt. We do have tools.

For starters, we have good systemic products that kill psyllids and that have been very effective in Florida on young trees – both as a preventative treatment and to already infested plants. It is applied to the roots and is absorbed by the plant - moving into the newer plant tissue. This is where the psyllids are feeding or laying eggs. It would probably work on older trees too but the rate would have to be quite a bit higher than is currently allowed. Putting this large amount on the trees, besides being illegal, might only make for super-resistant bugs. There are a few people looking into higher rates in order to save the more mature trees and this may be an option later on under certain conditions. We’ll have to wait and see.

Another important precaution is to watch your trees - especially the new growth - for signs of the insects. They’re small so you have to pay attention but they tend to like the outside trees of an orchard. If you can catch them early and kill them with a good insecticide, you may be able to keep things under control. The best time for spraying for maximum effect is just prior to the adult flush – to prevent egg-laying and subsequent feeding by the nymphs. In California, this timing isn’t worked out yet as well as it is in Florida, so we’ll have to pay extra careful attention until it is.

And remember, Southern California is now a war zone, and like any effective military effort, we need to anticipate where the enemy is headed. Quite simply, it is headed to any and all unprotected citrus plants. It’s true that citrus growers are the first that need to take precautions, but this is not enough. For every commercial citrus grower there are many more home owners that are not paying attention to the looming crisis. Growers need to make as large of a “no-fly” zone as possible around their trees. This means talking to neighbors and thinking like the enemy. It’s the newly-potted nursery plant sitting on an apartment balcony that’s going to be forgotten. We need snipers everywhere (polite ones, for sure). CDFA, for all their help, will never make this work alone. It’s time to bring out the troops. If we fail, we may lose the citrus industry in the Golden State.