Monday, July 22, 2013

LBJs (Little Brown Jobbies): Beetle Edition

The strikingly patterned eyed click beetle (Alaus oculatus) (Cary, NC).
It would be nice if all arthropods were as distinct as eyed click beetles (Alaus oculatus; above), harlequin bugs (Murgantia histrionica)  or black and yellow orb weavers  (Argiope aurantia). Although it would put me out of a job, it would also allow the public to better understand what insect, spider or millipede they are looking at in their garden or on their kitchen counter. 

Alas, many arthropods are difficult to identify or even impossible, especially just looking at them briefly. For example, in some species the male genitalia is the deciding characteristic - this makes female specimens unidentifiable to species or even genus. Others have many look-alikes or have not been well studied enough to find diagnostic traits to separate species. While these organisms may be very easily identified by experts, the public has very little chance of coming up with a name for the creature in question.

Some groups, however, are like black holes even to experts. I am sure every diagnostician can think of the group or groups in their field that have this characteristic. Among arthropods, I can think of a few: 
These groups share one thing in common: they all have many members which cannot easily be told from one another superficially, or at the very least from just looking at a photo online. 

The idea of blogging about this came to me last week when I got two samples into the clinic with superficially similar little brown beetles (another of these tough groups, and probably one of the most difficult).

Can you tell them apart? LBBs (Little Brown Beetles) representing 3 families and 2 superfamilies. Left - Mycetophagidae: Typhaea stercorea (Tenebrionoidea); Middle - Silvanidae: Ahasverus sp. (Cucujoidea); Right - Erotylidae: Cryptophilus sp. (Cucujoidea). All from North Carolina, USA [Photo by Matt Bertone]

One species (above left) was from garlic that had been left in a barn to cure after harvest. The other two (above middle & right) were found as adults and larvae in alfalfa hay. All three beetles were likely attracted to the fungus that was growing on these drying products which probably grew mold due to the humid and rainy weather we have been getting. All three are functionally similar, but taxonomically very different. There are over a dozen such families of small, brownish beetles that act very similar, infesting stored products, dried wood, and moldy areas (just look at some Cucujoidea to see how similar some are). Many are thus associated with human homes and product facilities where they feed either directly on the grains or on the microscopic molds that coat these products. Not only are they difficult for the layperson to identify, but most are also small to extremely small, making ID even more difficult:

Actual size of the beetles shown above. The largest (Left) tops out at just under 3 mm long! [Photo by Matt Bertone]

In the end, these arthropods are what keep people like me busy looking at them under a microscope at 70X magnification, counting the number of segments in their feet...

Tuesday, July 9, 2013

Fairy Rings and Fairy Tales

written by Lee Butler, NC State Turf Pathology

Fungi love water and here lately in North Carolina we've had plenty of water via record rainfall to help ensure they don't go extinct any time soon. The majority of fungi in this world are beneficial, because without these fungi we wouldn't have some of the finer things in life such as beer or Agaricus bisporus that adorns salads and pizzas as a topping. However, there are plenty of them that cause problems for us in the form of plant diseases.
Fairy ring mushroom (Photo: B. Shew)
You name a disease of turfgrass and we have likely observed it in the field or as a sample submitted to the NC State Turf Diagnostics Lab over the past 3-4 months. One that we rarely receive as a sample due to it's ease of identification is from a fairy ring. Most people associate fairy rings with mushrooms. To quote NC State alum Dr. Lee Miller, "not all fairy rings produce mushrooms and not all mushrooms produce fairy rings." This is important to remember, because if you observe mushrooms in your lawn, putting green, or croquet court, it doesn't necessarily mean you have a fairy ring problem.
A fairy ring in Raleigh, NC (Photo: Lee Butler)
Fairy rings have likely peaked the interest of mankind since day one. This fascination has led to some crazy theories over the years such as fairies danced there the night before or that it was created by the fiery tail of a flying dragon. Whatever you do, don't step into the ring, collect the dew from the grass blades, or attempt to destroy it because bad luck is guaranteed to follow!

"Plucked from the Fairy Circle" - A man saves his friend from the grip of a fairy ring.
From British Goblins: Welsh Folklore, Fairy Mythology, Legends and Traditions (1880)
Fairy rings tend to form in circles, arcs, crescents, or broken rings. During their radial journey outward, fairy ring fungi decompose organic matter, which in turn releases nitrogen and other nutrients back into the soil for plants to take up. This is why the ring will often be darker green than the surrounding turf. The good news is that fairy ring fungi don't actually infect the turfgrass plant like brown patch, dollar spot, etc. The bad news is that they leave behind a coating on the soil particles that renders the soil hydrophobic (repels water) and may ultimately kill the turf. This is important to know when it comes to controlling the symptoms caused by fairy rings. For example, if you are treating fairy rings curatively in a home lawn situation, your best bet may be as simple as punching holes through the dead rings with something as fancy as an aerification machine or as simple as a pitchfork. Either way, you are instantly helping water penetrate the affected zone. If you are only observing green rings, then you may be able to mask them with a light fertilizer application. In severe cases or in high profile areas, you will likely want to use wetting agents and/or fungicides in addition to the aforementioned tips.
Fairy Ring on NCSU Campus (Photo: B. Shew)
For more information about fairy rings, including control recommendations, click here.

Wednesday, July 3, 2013

Late Blight Has Arrived

Over the past 2 weeks, late blight, caused by Phytophthora infestans, has been knocking on the doors of our state. Aided by the monsoon-like weather we’ve been experiencing the past few weeks, our unwelcome guest has finally managed to get inside and start to wreak havoc. Late blight was officially confirmed on tomatoes from Guilford County on July 2nd. Today we diagnosed late blight on a tomato sample from Wake County and on a sample of tomatoes and potatoes from Watauga County.

Late blight can be a devastating disease on tomatoes and potatoes. Without proper preventative measures, late blight can completely defoliate and destroy a crop within one to two weeks.

The first symptoms of late blight on tomato leaves are irregularly shaped,
water-soaked lesions. (Photo: K. Ivors)
More information about tomato late blight and how to control it can be found in this tomato late blight factsheet produced by Dr. Kelly Ivors and in our earlier blog post

More information on potato late blight and how to control it can be found in this potato late blight factsheet produced by Dr. Lina Quesada-Ocampo.

Videos and additional management recommendations for tomato and potato are available in the USAblight website. Here you can track the late blight epidemic and register to receive text and/or email alerts when new disease outbreaks are reported.