Friday, December 20, 2013

The Heartbreak of Botrytis

Decay at the terminal portion of the flowering stem of
poinsettia, due to infection by Botrytis cinerea

Dark blotches are bract
infections by B. cinerea
On Monday, December 16th, we received a sample of poinsettias that for all commercial purposes had been ruined by Botrytis blight. Botrytis cinerea is a pernicious and ubiquitous fungus that particularly infects wounded or senescent tissue such as old flowers. From this foothold it can spread to other plant parts. When the fungus sporulates, the colors of the black conidiophores (spore-bearing threads) and white conidia (spores) combine to give the appearance of a gray mold. The spores are easily carried around on air currents.

Botrytis cinerea can wreak havoc with many different host species, even causing canker on rose canes and fruit rot on plants such as strawberry. More specialized species of Botyrtis also exist. One is Botrytis elliptica, which affects primarily lilies. Botrytis tulipae causes a disease called "fire" on - you guessed it - tulip.

Closeup of conidiophores and conidia of Botrytis cinerea,
growing on cyathia (true flowers) of poinsettia. Black bar = 1mm.
The Achilles heel of Botrytis is its need for abundant moisture. In greenhouses, care must be taken to ventilate, even for a while after sunset, in order to keep the relative humidity down. Watching watering practices (timing, drainage) is also important. Fungicides are sometimes needed. Another essential element in Botrytis management is prompt removal of dead plant material from the house. For more information on Botrytis in greenhouses, see our blog from May 18, 2012.

Pansy bed at NCSU in early 2012. Botrytis blight.
Be on the look out for Botrytis blight on pansies in the landscape, especially in the late winter and early spring. To prevent problems, avoid overhead watering if possible, and make sure the plant spacing and surrounding shrubbery allow for good airflow. For more information on Botrytis in the landscape, see the May 31, 2013 blog.
Light colored dead blotches on flowers, spreading to leaves,
are a hint that you might have Botrytis blight in your pansies.


Just a reminder to check our holiday closing schedule. We look forward to seeing you in 2014!

Mike Munster and Kelly Ivors

Wednesday, December 18, 2013

Songs of the Season, with a Twist



Are you tired of nonstop carols yet? While not as popular as Santa, plants star in many songs of the season – and some of them have special associations for us here at the PDIC. Number one on the list must be “The Christmas Song,” aka Chestnuts Roasting on an Open Fire. This song reminds us of the blight that devastated the Eastern forests in the last century, leaving us with no chestnuts to roast. “Oh, Christmas Tree” (Oh, Tannenbaum) makes us think of North Carolina’s beautiful Fraser firs and the root rot they must escape before they can end up in our living rooms. Mistletoe figures prominently in “I’ll be Home for Christmas” and holly pops up in “Have a Holly Jolly Christmas” and “The Holly and the Ivy.”

But here’s a song that puts me in the holiday spirit even though the subject and the tune have nothing to do with snow, presents, Santa and all the rest. That’s because for many years, NCSU Plant Pathologists sang it lustily at every gathering, including the annual holiday party. I promise you have never heard it on the radio. Enjoy!
Photo by David Langston, Univ. Georgia


For a nice write up about managing root-knot nematodes, check out this article by Pender County Agent Charlotte Glen.











THE NEMA SONG
(To be sung with gusto to the tune of “The Battle Hymn of the Republic”)

A nematode was chewing on a young tobacco root.
Her keen and piercing stylet was protruding from her snoot.
Her salivary glands were squirting out the poison juice.
The galls keep hanging on.

(Chorus)
We must fight the nasty nema,
We must fight the nasty nema,
We must fight the nasty nema,
Rotate crops and pray.

A cotton plant must suffer on a hot and sunny day.
It transpires too much water when its roots are chewed away.
If we don’t lick the nema we will really have to pay.
The galls keep hanging on.

(Chorus)
Meloidogyne incognita,
Meloidogyne incognita,
Meloidogyne incognita,
Fumigate and pray.

The cortex cells are swelling to a giant size to stay.
The female’s sac’s protruding in a morbid sort of way.
The blind roots now are forming and the root knot’s on the way.
The galls keep hanging on.

(Chorus)
We must fight the nasty nema,
We must fight the nasty nema,
We must fight the nasty nema,
Rotate crops and pray.

Lyrics by Dr. G. B. Lucas

Wednesday, November 27, 2013

Some Fungi You Should Be Thankful For

Ahem... For which you should be thankful.


Here at the PDIC we focus on the negative impacts of fungi, bacteria, nematodes, and viruses on plant health and human well-being. This tends to overshadow the fact that they do more good than harm in the grand scheme of things. Since we deal mostly with fungi, I offer several for which we should be grateful.

Saccharomyces cerevisiae helping in the kitchen.
Saccharomyces cerevisiae. The lowly baker's yeast is one of humanity's best friends in the fungal kingdom. It's a one-celled organism, whereas most fungi grow as thread-like "hyphae". More importantly, it's capable of fermentation, a process that starts with carbohydrates such as sugar and results in energy for the fungus and alcohol and carbon dioxide as byproducts. Without the yeasts, the rolls and stuffing on the Thanksgiving table would be unleavened, and there simply would be no wine, beer, or spirits at the celebration.

Mycorrhizal fungi at work, under the surface.
Plant Pathology Department Slide Collection
Mycorrhizae. When we look at a plant, we don't usually think about the roots. Even when we do think about roots, we usually forget that most plants partner-up with certain fungi that enable them to better extract nutrients from soil. This association is known scientifically as a "mycorrhiza" (plural "mycorrhizae"), which is simply Greek for "fungus-root". Other benefits have been ascribed to this relationship such as increased resistance to root diseases and other stresses. There are two basic groups: the ectomycorrhizae and the arbuscular mycorrhizae. The former are characteristically associated with trees and form a fungal mantle on the outside of the root, slightly modifying its structure and appearance. Often these fungi produce mushrooms or puffballs (above or below ground) when it comes time to reproduce. A good example is the small, reddish Russula mushroom we see popping up each fall in our area. The arbuscular mycorrhizae form on both herbaceous and woody plants, and are very inconspicuous. If you aren't a scientist dedicated to plant roots in some way or another, you probably won't ever notice them. Do appreciate them, though, as they are close collaborators with the plants we so value and need.

Brown cubical rot of pine wood, caused by the fungus Meruliporia incrassata.
Plant Pathology Department Slide Collection
Wood decay fungi. Yes, wood decay fungi are unwelcome when they invade living trees or our homes, but we’d be in deep trouble without them. They are a critical cog in the carbon cycle, degrading the cellulose and lignin components of wood. In fact, fungi are the only organisms in the world that produce the enzymes necessary to break down lignin. Without them we would be up to our eyeballs in woody debris. There are a number of spin-off benefits, as well. For example, pulping using these fungi will be better than current processes in terms of reducing both energy use and chemical waste.

Fungi with medicinal applications. We remember with gratitude the mold Penicillium, which brought about the antibiotic revolution. Apart from the penicillins, the cephalosporin antibiotics can also be traced to a fungal metabolite. The cholesterol-lowering drugs compactin and lovastatin are derived from fungal fermentation, although other statin drugs are synthetic or semi-synthetic. Traditional Chinese medicine makes use of a number of different fungi, some of which may find their way into the western pharmacopeia.

Agriculturally important fungi. Several fungi such as Beauveria bassiana and Metarhizium anisopliae are used as biological insecticides. Some such as Trichoderma harzianum are found in biological fungicides. Also, an important group of chemical fungicides, the strobilurins, were developed based on a chemical found in the mushroom Strobilurus tenacellus.

Farmed, or Farmer?
Neocallimastix and company. Probably the most obscure group on the list, it was only within the last forty years that these were recognized as fungi and not protozoans. This includes genera with such names as Orpinomyces, Piromyces, and Neocallimastix, Once known as the "rumen chitrids", they are better called "anaerobic gut fungi", "anaerobic zoosporic fungi", or simply "anaerobic fungi". They work together with bacteria and protozoans in the digestive systems of many kinds of herbivores to break down the fibrous diet of these animals. They are found in the rumen of animals such as sheep and cattle, but have also been found in deer, horses, kangaroos, even rhinos and elephants. They do a better job than bacteria at breaking down lignocelluloses, and their rhizoids can get through plant cuticles, which bacteria & protozoans cannot penetrate. We really should be thinking of cows as farmers, responsible for a large and diverse population of microbes that convert roughage into materials that the cows can metabolize.

Strawberry jelly ingredients. Where does the citric acid come from?
Agaricus bisporus and other edible fungi. These are probably what you first think of when you consider "good" fungi, though their contributions pale in comparison to the others listed above. Note that the portabella and crimini represent a strain of Agaricus bisporus, the same white button mushroom of pizza fame. Of course there are many other wonderful edible fungi out there. A number are more popular in oriental culture than in the west, but you've probably eaten Auricularia in oriental soups. You may not be aware, though, of your consumption of a product that is commercially produced using the mold fungus Aspergillus niger: citric acid. The next time you see "citric acid" on the label, think fungus rather than lemons! And whatever you eat, have a Happy Thanksgiving!

Read on to find out about Insects to Be Thankful For.

Some Insects/Arthropods You Should Be Thankful For

How much of this delicious bounty was influenced by beneficial arthropods?

As we sit down this Thanksgiving to our turkey, mashed potatoes, and stuffing (and of course gravy!), we often give thanks to various people and things that make our lives better. So in that tradition, here are some of the insects and other arthropods (in no particular order) that, throughout the year, enrich our gardens, homes and lives...many of which we would not normally acknowledge.

Paper wasps, hornets & potter wasps (Vespidae)

Paper wasps (Polistes sp.) may sting, but they also hunt down pestiferous caterpillars to feed to their young.
Though largely hated due their painful stings and sometimes aggressive nature, these wasps are very good at hunting soft-bodied insects in gardens. Their favorite food seems to be caterpillars, which are the bane of most garden plants. The truly social groups (paper wasps & hornets) have an entire colony to feed, so they often carry away numerous pests. However they also need to defend their many sisters, thus their stings. Maybe I should focus on potter wasps (Eumeninae), who are solitary but also provision their mud pots with several caterpillars for their young to feed on. While they can sting, they are not aggressive like their social cousins. There are also several groups of solitary hunting wasps (Sphecidae) that give their young paralyzed caterpillars, further solidifying wasps as beneficial predators.

A potter wasp's (Eumeninae) pot is getting ready to dry. The small hole in the top is big enough for mother wasp to add a number of paralyzed caterpillars before sealing it off for her young to feed.

Parasitic wasps

A minute wasp (Aphelinidae; approximately 1 mm long) perches on its tiny host - a scale insect.
These usually minute wasps don't sting us, nor are they often seen by us. However, their effects on pests are immeasurable (figuratively - there are certainly studies that have been done to measure their impact). Most lay eggs within a host, which hatch into tiny larvae that feed on the poor organism from the inside. Others attach to the outside of the host, slowly sucking it dry. There are several groups of Hymenoptera that do so, including the large superfamilies Ichneumonoidea (Ichneumonidae & Braconidae) and Chalcidoidea (many families). Along with wasps several other groups of insects, notably flies (the family Tachinidae for example), have members that parasitize pests.

This hornworm caterpillar (Sphingidae: Manduca) is on its last legs. Its parasites (a species of Baconidae) spin white cocoons after emerging, from their host.

Pollinators (and not necessarily the ones that come to mind)

This false blister beetle (Oedemeridae: Heliocis repanda), like many beetles, loves nectar and thus also comes in contact with pollen which it may transport to many flowers.
I am sure you have already thanked butterflies and bees (both honey and bumble) for pollinating the plants we need to survive and enjoy looking at. However, there are numerous other insects that transfer pollen from flower to flower. Beetles, flies, bugs and even earwigs can be pollinators . In fact, any insect that visits flowers has a chance to pollinate. One of my favorite pollinators (as it should be yours as well) is a genus of tiny little biting midges (Ceratopogonidae). Without some of these [sometimes nasty] flies, we would not have one of life's greatest foods - chocolate! These flies are the only things that pollinate the cacao plant (Theobroma cacao), being small enough to fit inside the diminutive flowers.

Even earwigs (Dermaptera) enjoy nectar and pollen every once in a while. This one is covered in pollen which will likely rub off on another blossom, propagating the plant.

Flies

Larval black soldier flies (Stratiomyidae: Hermetia illucens) are powerhouses of decomposition, frequently obliterating compost waste.
Yes flies (Diptera) are sometimes annoying. And many transmit diseases or are pests. However, a large percentage of flies breed in decaying organic matter as larvae. This huge clean-up crew is responsible for devouring both rotting animal carcasses (which would be fun to have hanging around, right?) and vegetable matter. Proof of the latter can be easily seen by those who compost their yard waste and table scraps. Without flies we would be knee-deep in a putrid, bacteria-ridden mess - not something that would be good for your Thanksgiving appetite. Some flies are also important predators or biological control agents of weeds, to name a few good deeds done on two wings.

Energetic and beautiful, long-legged flies (Dolichopodidae) scour leaves to hunt down small insects including many pests.

Dung beetles

Even small dung beetles like this Onthophagus tuberculifrons can help bury dung and keep the ground clean.
As with flies cleaning up decaying matter, dung beetles get rid of another resource we find disgusting - excrement! These busy beetles (mostly Scarabaeidae) eat and bury dung for their young to feed on, effectively removing the foul substance from the ground surface. This has long been know to aid in pasture health by allowing grass to grow, aerating soils, destroying the breeding grounds of pest flies and worms, and returning nutrients to the soil. Instances where dung beetles are lacking have proved highly detrimental to natural and production ecosystems. Some are also quite beautiful and have amazing behaviors too.

The rainbow scarab (Phanaeus vindex) is one of our most beautiful beetles, despite spending a large amount of time covered in dung or underground. This male also has an impressive horn.

House centipedes

Although only a wee baby, this house centipede (Scutigeridae: Scutigera coleoptrata) is a fierce predator in the home.
Surprised by this? Despite their frightening speed and creepy leggyness, these centipedes (Scutigera coleoptrata) are good at hunting down and devouring household pests like flies and cockroaches. Though venomous, they rarely bite and most often use the venom to subdue things you really should be afraid of.

Ants

This fire ant (Solenopsis) is removing soil from its nest. Colonies of fire ants can be a good thing for your garden.
Again, although there are some ants that are not so great - those that sting and tend pest insects come to mind - many species of ants are very good at cleaning up waste, planting seeds and eating pests. For example, though fire ants are loathed for their stings, they can be very effective predators of crop pests. They are also effective, like earthworms and dung beetles, at aerating and churning massive amounts of soil.

Ticks

Just kidding! There is really nothing good I can say about ticks. Though I respect them for their fortitude and tenacity, there is really no good reason for them to exist except to suck blood and transmit diseases (which they really can't be blamed for - pathogens just love to use ticks to spread).

------------------------------------
Final thought
There are many arthropods that directly or indirectly benefit us and the ones listed above are just a starting point. Almost every group can have some quality that deserves our thanks - you just have to observe them in your garden or read the latest information to get a good idea of who the good guys are. It is also good to remember that "beneficial" is in the eye of the beholder - the advantages of arthropods must be weighed with the situation (e.g. some pests can be beneficial and vice versa).

Wednesday, November 20, 2013

Uninvited Holiday Guests

Insects, like all animals, must survive the winter (in one way or another) to reproduce the next year. There are two main strategies to do so: migrate or "hibernate". Of course there are famous insect migrations including monarch butterflies (Danaus plexippus) and several species of dragonflies (Odonata). However it is much more common for insects (and other arthropods) to hunker down for the winter in a nice secluded place. Insects overwinter in different life stages - either as eggs, larvae/nymphs, pupae (if they are holometabolous), or adults. The stage that overwinters usually depends on the type of insect, but sometimes can be determined by environmental or geographical factors.

Thus, as the days begin to cool and darkness descends earlier in the evening this holiday season, you may be getting more than your in-laws invading your home. Most do so by finding a nice brightly-colored home as a landmark during warm days where they aggregate on the siding, in eaves, or along windows. The most common nuisance insects overwinter as adults that may become active within homes during warm days of the season - a common occurrence here in NC which has a mild, fluctuating winter. Mass movements of these insects into living areas can be difficult to deal with and are a real annoyance. The following are some of the more common insects to enter houses.

- True bugs (Hemiptera) - the worst offenders -

Kudzu bugs aggregating in the crack of a tree; could easily be a window or the gaps in the siding of a house.

Bugs are among the most common insects found aggregating on and entering homes in the cooler months. Their numbers and the pungent smell they produce (they're not called stink bugs for nothing!) can be bothersome to people that want to enjoy the comforts of their indoors. Although bugs are generally harmless, kudzu bugs (Plataspidae: Megacopta cribraria) are sometimes known to cause irritations on skin, brought about by the secretions they produce. Brown marmorated stink bugs (Pentatomidae: Halyomorpha halys), another recent introduction into the US, also find it nice and cozy in houses. Along with these invasive bugs, many other types, including leaf-footed bugs (Coreidae: Leptoglossus) and boxelder bugs (Rhopalidae: Boisea trivittata), enjoy breaking and entering for a nice place to hibernate.

Kudzu bugs: one is alright, but hundreds are bad news!
Brown marmorated stink bugs find your home when it's cold outside.
Leaf-footed bugs may be seen around the home.



- Flies (Diptera) - can we use your attic? -

Figure from Oldroyd's magnificent book, The Natural History of Flies (1964). 

Several groups of flies will spend the winter in attics, barns and other man-made structures, safe and cozy away from the elements. The most common are called cluster flies (Calliphoirdae: Pollenia sp.), named for the fact that they often "cluster" in groups of hundreds in the attics of homes. Normally they are out parasitizing earthworms, but in the fall and winter when things slow down they get the urge to swarm homes. Face flies (Muscidae: Musca autumnalis) will also do this, usually around areas with livestock, their primary food (larvae live in dung and adults feed on facial secretions). On warm days these flies may come out of hiding to stretch their wings, much to the dismay of homeowners.
Cluster flies are drab (for blow flies) and have golden hairs on their thorax.

- Ladybugs (Coccinellidae) are pretty - but get them out of my house! -

"Ladybugs are great, right? They eat all the pests and are nice to look at." Tell that to someone whose living room is overrun by these red and black beasts. Most ladybugs do a fine job of staying outside and being good neighbors. However, one species in particular (though there are a few others) - the multicolored Asian ladybug or harlequin ladybug (Coccinellidae: Harmonia axyridis) - loves to come into homes. This highly variable species was first introduced into the US in 1916 for the control of pests and has been readily available for farmers and homeowners to purchase. In the 1980s it finally became established, and is now the dominant ladybug in much of its range. Thus there have been some concerns about this species. First, it may be pushing out native ladybugs with its voraciousness, which is not good for our biodiversity. Second, it can be structural nuisance pests. Along these lines, when they do enter homes in large numbers they can sometimes bite people and, like many ladybugs, reflexively bleed a noxious substance that may cause skin irritation and allergic reactions. For both of these reasons, the cartoon-like insects can be less funny than they are nightmare inducing.

Multicolored Asian ladybugs, though sometimes beneficial, are often a nuisance.

- So what can you do about it? -

The best way to deal with these insects is to first make sure that they cannot enter your home. Search for cracks and holes in the siding or under eaves. Any crack or hole small enough for the average insect to enter should be repaired or covered. While pesticide sprays on the South sides of the home may kill or deter some insects, they are not long-lasting, nor are they particularly effective. Once in the home, it is best to vacuum the insects up and collect them into hot soapy water or freeze to kill them. Spraying indoors usually does more harm than good, so cultural practices mentioned above work best.

Tuesday, November 5, 2013

About that pumpkin....

So Halloween has come and gone, but it's still Fall (Thanksgiving's on the way!) and everything is already red, yellow and orange. Why not keep that pumpkin spirit going?

Happy pumpkins are just glowing! (Photo by Matt Bertone)

Unfortunately, chances are by now your pumpkin is looking more like this:

This pumpkin used to be happy. (Photo by Sara Prado)

If you're lucky you can get it to the trash or compost without the bottom falling out (I wasn't that lucky). Even if you didn't carve a scary face in it, it will likely be in decline seeing as it is a fruit off the vine and it is slowly being broken down by bacteria and fungi. If there is a wound on the pumpkin from rough transport, it opens the pumpkin to these microorganisms. This is prime food for many insects that love to eat the nutritious soup.

Most of these insects are flies. Flies love rotting vegetable matter. Vinegar or fruit flies (Drosophilidae) are particularly fond of rotting fruit. Some walk all over their giant bounty, waving their patterned wings around while seeming to dance. They do this to attract mates and establish that they have found a nice source of food for their precious little maggots.

This vinegar fly (Drosophilidae: Chymomyza amoena) may have a dance party on your over-ripe pumpkin.

Other common flies include dark winged fungus gnats (Sciaridae) whose larvae love to eat the molds and other fungus growing happily on the pumpkin flesh. The small black flies swarm around the pumpkin and settle after a disturbance.

A mating pair of dark-winged fungus gnats (Sciaridae) - a scene you may see on your rotting pumpkin.

Many other fly species may be found among the decaying Jack-O-Lantern as well. However, flies aren't the only visitors to such a great source of food. Beetles, earwigs, isopods (sowbugs & rolly-pollys), slugs/snails, and other organisms like this type of substrate to feed on as well.

Picnic beetles (Glischrochilus) and other Nitidulidae love rotting vegetation. This is from last year's pumpkin.

Isopods may nestle themselves inside or under the pumpkin to feed.

"I am looking for a nice moldy pumpkin pie" says the snail. Slowly, he might find yours....

Of course, if you are responsible and discard your pumpkin while it is still fairly fresh, you won't have to deal with these insect and other small animals. But then again you may not see some of these cute little critters setting up shop and recycling your autumnal fruit festivity. Oh well, they can find the compost bin too I guess...

Thursday, August 8, 2013

Pesky Blackberry Foes

Here in North Carolina, blackberry season is in full swing! For many North Carolinians, that means it is the perfect time to stock up their freezer or pull out those ball jars and can up some tangy black berry jam. Blackberry season brings back sweet summertime memories of riding my bike down the road to the black berry thicket at the edge of the woods, gorging myself with fresh, juicy berries (probably picking up a few chiggers in the process), and heading home with purple stains on my hands, face, and clothes. Whether you prefer to pick your own berries or buy a pack from the local Farmer’s Market, we can all agree that blackberries are a signature snack for a late summer’s day. Unfortunately, blackberries, like all things delicious, come with their fair share of pests and diseases that impact fruit production.

This summer, we have seen two similar but different diseases on blackberry samples: orange rust of blackberry and black raspberry and leaf and cane rust of blackberry. Orange rust is typically the more devastating disease because it can become systemic, moving from leaves into other parts of the plant. The orange rust fungus has two forms, Arthuriomyces peckianus (formerly Gymnoconia peckiana) and Gymnoconia nitens, which differ only in the number of spore stages produced. Pustules full of orange-yellow spores develop on the undersides of leaves in late May and early June. These spores are blown to healthy leaves and infect when humidity is high and leaves are wet. Heavily infected leaves may die and defoliate. Once the plant is infected, the rust fungus becomes systemic. It grows down the infected shoot, into the crown, and then can enter newly formed roots. Symptoms associated with shoot infections include proliferation of shoots, weak and spindly canes, and lack of spines on the shoots. In mid- to late summer, brownish black pustules that contain dark teliospores develop on the undersides of lower leaves. Teliospores do not infect, but germinate to produce basidiospores that can infect new buds or shoots, or the teliospores can overwinter on leaves before producing basidiospores the following year. Infected plants remain infected throughout their lifetime and do not recover.
Orange rust pustules on underside of leaves. Note leaf distortion. (Photo: PDIC Database)
Orange rust does not kill the plant outright, but infected plants are completely lost to production due to their inability to produce blossoms and berries. Controlling orange rust is largely achieved through cultural practices. Plant disease-free stock plants, eradicate diseased plants and wild berries in the surrounding area, and completely remove and destroy the entire plant as soon as symptoms develop on canes or leaves. Thin healthy plants to promote air circulation and to reduce leaf wetness.

Leaf and cane rust is caused by the fungus Kuehneola uredinis. Leaf and cane rust produces yellow spores in pustules that split the bark of infected canes, causing them to become weak. The pustules can also be found on the undersides of leaves. Diseased old canes should be pruned after fruiting. Alternate-year fruiting programs can help reduce disease pressure, and routine fungicide spray programs may be effective in preventing new infections. 
Leaf and cane rust. Note yellow spores bursting from cane. (Photo: NCSU Database)
Leaf and cane rust.  Infected leaves maintain shape unlike
those infected with orange rust. (Photo: NCSU Database)
Care must be taken to differentiate systemic orange rust from leaf and cane rust because leaf and cane rust does not require drastic removal methods to control disease. Identification of the rust pathogen requires a microscope and considerable knowledge in rust morphology. Suspect samples should be sent to the Plant Disease and Insect Clinic for a formal diagnosis.

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.