Landscape Professional Field Day 2013

Post co-written by Matt Bertone & Mike Munster

Attendees enjoying the nice weather!

On May 15th, the NCSU PDIC set up shop temporarily at the 2013 Landscape Professional Field Day, held at the beautiful JC Raulston Arboretum. This small gathering focused on a half-day program of informative talks for those working mainly with landscape woody ornamental plants. While industry reps were showing their wares and the speakers were informing attendees of the newest issues in landscaping, we brought our microscopes and tools to get down and dirty with samples brought to us by meeting members.

Mike at the booth, full of samples from us and clients.

We prepared for it the day before by scouting local plants for disease and insect damage to use as "show-and-tell" examples. From the clinic we brought an arborvitae riddled with weevil damage (see this post for details), imported willow leaf beetles (one of the individuals seen here), Armillaria infected wood and a few other things. Matt brought in a number of samples from his yard including maple eye-spot midge galls, some dogwood with powdery mildew, camellia leaf gall (Exobasidium camelliae) and oak leaf blister (Taphrina caerulescens). We also had a Nandina showing "shoestring" foliage typical of infection by Cucumber mosaic virus.

Mike identifying diseases for a client.

Throughout the day we met new people and caught up with colleagues and clients. A few brought us some problems to diagnose, including an unhappy trio of containerized Liriope, one of which had classic symptoms of Fusarium crown rot. There was a sample of Eastern red cedar (pictured at right) that had to be brought back to the lab for diagnosis. Symptoms of Phomopsis tip blight and Kabatina tip blight are very similar. This one turned out to have Kabatina.A yucca leaf from there at the arboretum was found to have anthracnose, caused by the fungus Colletotrichum.

Matt at the scope with some sort of critter.

On the critter side, a client brought some lovely tree hoppers (see below) that were congregating on an oak in Wake Co. Matt assured him they were merely flashy and would not harm a mature oak. Later a graduate student working on witch-hazel (Hamamelis) at the arboretum was curious about strange growths on the leaves of the trees. Matt would tell you what they are, but that would ruin an upcoming blog post about them!

An oak treehopper (Platycotis vittata). Males and females may be horned or hornless.

All in all it was a beautiful day and it felt good to get outside - warm weather, interesting people/samples and a grill full of hot dogs makes for a great time! Until next year...

No Joke: Tomatoes are Cracking Up

Photo: Debbie Roos

Tomatoes are cracking up after the recent rains, but growers are not amused. Recently, we’ve seen in an increase in the amount of tomato surface cracking. Tomato cracking is an abiotic disorder of tomato fruits that is associated with growing conditions. When tomatoes are left on the vine too long or during periods of rapid fruit growth, the tomato epidermis (or skin) does not have enough elasticity to compensate for the sudden growth. Eventually the skin splits and bursts.

There are two main types of growth cracks 1) radial cracking, which is splitting of the skin from the stem scar towards the blossom end and 2) concentric cracking, which is splitting of the skin in a circular pattern around the stem. Radial cracks occur during humid, hot weather. Concentric cracks occur during rapid fruit growth associated with rainy weather following a period of dry weather. The earlier growth cracks occur during fruit development, the more damaging they are. Growth cracks can provide the perfect entry point for secondary fruit rotting organisms.

Photo: Debbie Roos

The most important means of controlling growth cracking is maintaining a steady, adequate supply of water or irrigation flow, especially during hot, dry conditions. Avoid over and under irrigating. Mulching also will help prevent dramatic fluctuations in soil moisture. Be especially wary if weather was cool and overcast followed by sunny, hot, and dry periods, and then high humidity and rainfall. Keeping foliage healthy and disease free is also critical. If the fruit lacks leaf cover, cracking can be more of a problem. Remove mature fruit right after heavy rains to prevent cracking. Follow recommendations from Cooperative Extension about plant nutrition, because high nitrogen and low levels of potassium can contribute to fruit cracking. Some varieties are more prone to cracking and can show cracking when the fruit are still green. Even varieties that show some resistance to cracking in the green stage may crack once the fruit starts turning red. Plum varieties like ‘Heinz’ and ‘Marglobe’ crack less than cherries and the larger fruited varieties like “Better Boy.” If you have a history of tomato cracking in your tomatoes, you may try switching to one of these varieties, ‘Daybreak’, ‘Jet Star’, ‘Pink Girl’, ‘Monte Carlo’, ‘Mountain Fresh’, ‘Mountain Spring’, and ‘Spitfire.’ New varieties are released regularly, so check with your local cooperative extension agent for latest variety recommendations for tomatoes.

by: Emma Lookabaugh, Chris Gunter, and Barbara Shew

Proud Papa - Twice in One Month!

As I revel (quite sleepily) in the fact that I have a new little daughter, I am also very happy that my other babies from a clinic sample have been "born". Since I started this position I have been watching a trunk section of arborvitae (Thuja sp.; 'Green Giant' variety) that was submitted from Holly Springs (Wake Co.) following the decline and death of some trees.

Affected arborvitae (Thuja sp.) along the road.

When I first saw the section I observed a few large holes - about 1/4 inch in diameter - in the top with sawdust being pushed from them. This was clearly a boring insect, but was it a metallic wood borer (Buprestidae), longhorn beetle (Cerambycidae), or something else? Turns out, after prying some of the bark back, there were several large (up to 3/4 inch), legless larvae boring just under the surface. The larvae were very clearly weevils (Curculionidae), but what species?

Weevil larvae preserved for future study.

Because larval weevils are nearly impossible to identify, it was my goal to rear the larvae until they emerged as adults so I could then identify them. I waited...and waited...and waited. Some beetles (under the right conditions) can exist as larvae in wood for decades and even up to 50 (!) years - I wasn't going to wait that long. Fortunately, after removing a little more bark some weeks later I found pupae. Finally, adults in progress! A week or so later and I had adults which I identified as the cypress weevil (Eudociminus mannerheimii (Boheman)).

Cypress weevil (Eudociminus mannerheimii) showing life stages and damage.

This fairly large weevil (10-17 mm) is known from a few hosts, especially baldcypress (Taxodium distichum), but also Japanese cedar (Cryptomeria japonica), Leyland cypress (Cupressocyparis leylandii), and arborvitae (Thuja sp.). It's biology appears to be similar to the related pine regeneration weevils, Hylobius pales (Herbst) and Pachylobius picivorus (Germar). The beetles lay eggs on weakened or dying trees and the larvae burrow beneath the bark before creating a deeper hole to pupate in. Adults appear to emerge in the Spring and will feed on the bark of small, green branches. Because they generally attack already-declining trees they are not always the main issue. However, this sample had so many weevils in one small section that I believe they were a major factor causing health issues for the trees. Follow the links below to read more about this weevil and learn about management practices. In the mean time I am going to smoke my proverbial cigar and curate these specimens to go into the NCSU Insect Museum which only had four total specimens!

LINKS:
NCSU Entomology Insect Note on Eudociminus mannerheimii
UF Featured Creatures on Eudociminus mannerheimii

Be on the Lookout for Cedar Apple Rust

Most of us who live in the triangle are hoping for rains to wash away the yellow film of pollen coating our cars, houses, and sidewalks. Spring rains also jump start the most bizarre life-stage of cedar apple rust, a common disease that affects apple trees (and crab apples) and eastern red cedar trees.

Galls on cedar (Photo: H.D. Shew)

The cedar apple rust pathogen (Gymnosporangium juniperi-virginianae) requires two hosts and four spore stages to complete its complex life cycle. On cedar trees, the most obvious signs of infection are firm brown galls, which are about the size of a golf ball and are usually found scattered on the tree’s branches and twigs. After a heavy rain, the galls produce striking bright orange gelatinous horns, which are composed of millions of spores called teliospores. In dry periods, the horns can be seen as short spikes covering the galls. If you find a gall with dried horns, cut it out of the tree, place it in a glass of water and watch over the next few hours as the horns expand.

Gall with dry telial horns (Photo: H.D. Shew)

The cycle of wetting and drying can continue several times during the spring, and in each cycle the teliospores germinate and give rise to another spore type, called basidiospores. These basidiospores are forcibly discharged into the air and are wind-blown to nearby apple trees.

 Apple leaves and fruit are most likely to be infected when they are wet and temperatures range from 46 to 75 F. Yellow to orange spots are produced on the upper surface of the apple leaves one to two weeks after infection. The spots on leaves may be raised or swollen and infected fruit may be slightly distorted. Small black dots within the lesions signal the production of the next spore type, the pycniospores (also called spermatia). One to two months later, fringed cup-shaped structures (aecia) appear on the underside of the apple leaves and these contain aeciospores, yet another spore type.

The aeciospores are windblown to cedar trees in late summer to early fall, where they germinate and infect to produce galls. The galls produce teliospores in the second year after infection, completing the life cycle. G. juniperi-virginianae survives in the gall tissue for only two years. After its second year, the spore producing year, the pathogen dies in the gall tissue. On apples, the pathogen survives only a few months, just long enough to produce the aeciospores that infect cedar trees.

Symptoms on apple (Photo: E.C. Lookabaugh)

Cedar apple rust causes only minor damage to cedar trees from twig dieback. Damage to apple is more significant and can result severe defoliation and fruit blemishes. Since this pathogen requires both hosts to complete its life cycle, control can be achieved by eliminating one host from the surrounding area, although oftentimes eradication is not feasible or desirable. Additional control measures include the use of disease-resistant apple cultivars, properly timed fungicide applications on apple, and removal of cedar galls before spring rains.

Check out this cool video of telial horns expanding (Video: Arlene Mendoza-Moran)

More information about the 2013 strawberry virus outbreak

Many of you probably have seen an article in today's Raleigh News and Observer about virus problems in this year's strawberry crop. The Plant Disease and Insect Clinic has received several strawberry samples with virus problems in the past few months.

Here are some comments from Dr. Frank Louws, Extension Specialist for Strawberry Diseases in NCSU's Department of Plant Pathology about the strawberry virus situation:

This link will take you to an excellent article from Dr. Chuck Johnson at Virginia Tech about this year's strawberry virus outbreak. All the information for Virginia is true for NC and other states with this problem. The main question growers ask is: “What can we expect in yields?”. We have only limited experience with these viruses in our annual systems. However, we had a case of Strawberry Mild Yellow Edge Virus (SMYEV) in 2004, as shown below in Sweet Charlie plants photographed at full harvest. About 25 to 30% of the plants were affected by the virus and the virus dramatically affected plant growth and yield, as seen in the picture. This year, two viruses, SMYEV and Strawberry Mottle Virus (SMoV), have been diagnosed from problem fields. We do not know how these viruses will affect crop yields in 2013, but some reductions are expected. Specific recommendations for dealing with this problem can be found in Dr. Johnson’s article. With good management, this problem should not recur in future years. 

Leptoxyphium, an Unusual Sooty Mold

Ornamental sweetpotato leaves with sooty mold at the petiole/blade junction

The sooty mold Leptoxyphium on the underside of an ornamental sweetpotato leaf

This blog is going to be a bit more technical than many of my posts, but I hope you'll find it interesting. A recent sample of ornamantal sweetpotato leaves from a greenhouse showed dark fungal growth at the top of the petiole and on the upper and lower surface of the leaf, just at the point of petiole attachment. The colonies could be scraped off easily, which is typical of sooty molds. The fungus was sporulating freely, with conidia (asexual spores) produced in drops of liquid at the tops of dark synnemata (tiny columns of fungal hyphae).

Synnemata of Leptoxyphium sp. on sweetpotato leaf

Top of a synnema of Leptoxyphium, at 400x

Using Seifert & Okada's key to synnematous hyphomycete genera in the 2011 book "The Genera of Hyphomycetes", the identification was made to the genus Leptoxyphium. The name means "slender sword" in English, possibly referring to the shape of the synnemata, but it is interesting that there are also awl-shaped (subulate) cells around the fringe of the spore-bearing area. This genus is also described on pp. 777-782 of Stanley Hughes's 1976 paper "Sooty Molds" (Mycologia 68(4): 693-820). Leptoxyphium species are a tropical to subtropical sooty molds, and rather unusual in that they often grow in association with glands and glandular trichomes of plants, rather than on insect honeydew. The good news for the greenhouse producer is that while it is an asethetic issue, this fungus is not going to harm the plants.

Meet Our New Vegetable Pathologist

Hello, my name is Lina Quesada (pronounced Lena Kesada in case you were wondering). On March 1st of 2013 I joined the Department of Plant Pathology at North Carolina State University as an Assistant Professor and Extension Specialist for vegetable pathology. I am originally from Bogota, Colombia (not Columbia!) and came to the US in 2006 to work on late blight of potato at the Ohio State University.

Shortly after that I moved to Lansing, Michigan and started a PhD in Plant Pathology at Michigan State University working with Phytophthora capsici, an important pathogen of cucurbits and solanaceous crops. While working on my PhD I fell in love with the boy in the lab next door and married him on 2010, the same year I finished my PhD.

I stayed at MSU and did a postdoc working on cucurbit downy mildew and bacterial canker of tomato. After that I did another postdoc working on corn postharvest diseases caused by Fusarium, a soilborne pathogen that can also affect sweetpotatoes and vegetables. My husband and I moved to NC a few weeks ago and have really enjoyed this beautiful state and its kind people. I am very excited to be here and have the opportunity to work with the clinic and all of you during the next few years to address challenges you have with vegetable diseases. If you need to contact me my information can be found here.  You can follow me on Twitter, Facebook or LinkedIN if you wish and I am in the process of making a lab website that will be posted to the link I just provided to quickly disseminate any findings or materials produced by my program.

The New Bug Guy

Hello everyone! My name is Matt Bertone and I am the new entomologist for the Plant Disease & Insect Clinic. I will be taking over for the now-retired Dave Stephan, a great entomologist with years of encyclopedic knowledge who will not be easily replaced. I do hope to follow in his footsteps, however, and to learn as much as I can about the insects and other animals that affect the daily lives of North Carolinians. But first, let me tell you a little bit about myself.

I was born up North (don’t hold it against me) and lived most of my formative years in Pennsylvania. From a young age I was obsessed with the natural world (see below photo). It started with the usuals like dinosaurs and such, but quickly turned into a passion for insects, spiders and other creepy-crawlers¹. They were so strange and diverse that there was always something amazing to learn.

Only the nerdiest kids know how to draw
a microscope in kindergarten.

After high school I entered college at Salisbury University on the Eastern Shore of Maryland. I had a great time there and took as many zoology courses as I could. There I met many great scientists and was introduced to research studies and continuing to graduate school. I was not aware of the universities that had entomology programs and applied to NCSU on a whim after seeing one of my colleague’s certificates from the department. After applying I was very happy to be accepted and had no idea how wonderful the area, school and people were going to be.

In 2001 I started my master’s work on dung beetles (Scarabaeidae & Geotrupidae) inhabiting cattle pastures in the Piedmont (Salisbury, NC) and coastal plains (Goldsboro, NC) under the advisement of Dr. Wes Watson. The project was great. I was introduced to a charismatic group of insects, researching their seasonality, abundance and diversity, and performing experiments to show how they help fertilize different soils. I was also happy to participate in extension work, since teaching in any format is another passion of mine.

A rolling dung beetle (Melanocanthon bispinatus)
from North Carolina.

In 2004 I began my PhD work under Dr. Brian Wiegmann on the evolution of true flies (Diptera), one of the most underappreciated – yet extremely diverse – groups of animals. I used genetics to see how different groups of the more “primitive” flies, like mosquitoes and midges, were related to one another. It was eye opening to learn the things flies do and I could (and may well in the future) go on and on about them. Needless to say, I found another group to love².

The elephant mosquito (Toxorhynchites), a large and distinctively blue fly, 

is one of the few beneficial mosquitoes. Larvae eat other mosquito larvae and adults do not bite. This male was sucking goldenrod nectar in Garner, North Carolina.

Following my degrees I have worked on various projects including a computer-readable glossary for the anatomy of wasps, bees and ants (Hymenoptera) and a citizen science project on the arthropods (insects, spiders and relatives) that are found in Triangle homes (a project through NCSU and the NC Museum of Natural Sciences).

Now I’m here in the clinic! I am very excited to help people find out what little leggy things are on their plants, eating their crops, and inside their homes. Please feel free to send photos or specimens to the clinic. I will do my best to get an ID, so that a specialist can recommend the proper action. All said, I hope to serve science and the citizens of North Carolina well in this position!

Other facts about me:

• I am a huge (literally and figuratively) insect geek, competing in many insect quiz bowls (Linnaean Games) during my time at NCSU
• I am an avid insect macrophotographer (my Flickr) and graphic designer
• I enjoy music, movies, games and cooking
• Last but certainly not least, I have an amazing wife and daughter, and a baby on the way (as well as two dogs)

¹ I also love reptiles, amphibians, fish, and many other groups of organisms (even plants!)
² I highly suggest anyone interested in flies read Harold Oldroyd’s captivating tales in The Natural History of Flies – it is very easy to read except for some scientific names (which you can just pretend are like the variously named creatures from Tolkien or Dr. Seuss!)