Saturday, June 30, 2012


Pest Alert for week of June 11, 2012
Impatiens downy mildew detected in multiple landscape locations in North Carolina

Downy mildew of impatiens is caused by the ‘fungus-like’ organism Plasmopara obducens. The group of organisms that cause downy mildew diseases are not true fungi- they are more closely related to the well-known plant pathogens Phytophthora and Pythium than they are to true fungi. This is an important distinction to understand because many of the traditional fungicides used to control fungal diseases of plants do not have efficacy against the downy mildews.  All types of propagated Impatiens walleriana, including double impatiens and mini-impatiens, and any I. walleriana interspecific hybrids, such as Fusion® impatiens, are susceptible to downy mildew; however, all New Guinea impatiens (I. hawkeri) and interspecific hybrids such as SunPatiens® are tolerant to downy mildew. No other bedding plants are known hosts of this particular downy mildew, although there are a few other downy mildew species that attack other floriculture plants like coleus and basil.

What does downy mildew look like?
A really good resource about identifying the disease, as well as disease control information, can be found at: http://e-gro.org/pdf/Bulletin_1-8_Impatiens_Downy_Mildew.pdf

In addition, a webinar presented by Dr. Colleen Warfield of Ball Horticultural Inc. can be found at: http://go.ncsu.edu/impatiens_downy_mildew_webinar

Pictures of a few plants with downy mildew from the landscape in North Carolina are pasted below.


 

Downy mildew likes cool, wet/humid environmental conditions. The current conditions we’ve experienced recently across the state of North Carolina are conducive for this disease. The important thing to remember is that downy mildew is spread by wind currents, water splash or by the movement of infected plants. We know that the disease is now in our area and that the spores of the pathogen have the ability to spread long distances in air currents. Be on the look-out for it! So far it has been confirmed in both the western and piedmont areas of North Carolina.

Fungicide treatments are not recommended for plants in the landscape; instead, all infected impatiens should be pulled from the landscape and destroyed. Fungicides are not always 100% effective at eliminating the disease. Allowing infected plants to remain in the landscape may allow the pathogen to overwinter as resting structures (called oospores), which can start a new epidemic later in the year or in following years if impatiens are replanted in the area. New Guinea impatiens, coleus, begonia, or other available bedding plants are safe to reset in the affected area.




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Pest News for Week of July 2nd


ORNAMENTALS AND TURF
From: Steve Frank, Extension Entomologist

Notching on Redbuds by Bees

Leaf cutter bees in the family Megachilidae are actively notching out small pieces of leaves from redbuds and other trees. They also attract attention for tunneling into soft rotten wood and hollow or soft, pithy plants stems like roses. They make their nests in these hollow tubes and line them with leaf fragments. Leaf cutter bees are of much more of a benefit than a pest. Try to convince clients of this but also most insecticides are either not labeled for bees or ineffective since the bees do not eat the leaves. Many people are more concerned about the bees tunneling in their roses which can be prevented by sealing the ends of branches after pruning. Overall these are an important native pollinator that should be protected and even encouraged.

More pictures: http://ecoipm.com/
Information sheet: http://www.ext.colostate.edu/pubs/insect/05576.html/


Catalpa Defoliation

I had a report this week that a catalpa tree on campus was completely defoliated by sphinx moth caterpillars. Caterpillars in general can make short work of trees when they really get going. Look for chewing damage and frass on leaves. If you find a few big caterpillars you could pick them off. It is probably late at least in Raleigh to implement much control since it sounds like they are about done. These big beautiful caterpillars become big beautiful moths. The adult ‘hawk moths’ hover around flowers feeding on nectar and are often mistaken for humming birds.


From: Lee Butler, Extension Assistant, Plant Pathologist

Summer Solstice Welcomes Brown Patch

June is in full swing and so is brown patch in tall fescue lawns and landscapes. Brown patch, caused by the fungus Rhizoctonia solani, is the most common disease in tall fescue during late spring and throughout the summer months in North Carolina. Brown patch infections can start as early as April in some years with full blown outbreaks occurring by late May and early June in most years. As the name implies, symptoms are brown to tan areas of turf that are roughly circular patches that range from a few inches to several feet in diameter.

The two most common mistakes managers of tall fescue make are fertilizing too late or too much in late spring and over watering. Tall fescue should not be fertilized after the first of May, unless you are using ultra low rates (< 0.25 pound N/M) with iron for a color effect. The recommended amount of nitrogen on tall fescue per year is 3 to 4 pounds per 1,000 square feet. Most people will apply a pound or two in the fall and a pound or two in the spring. When in doubt, submit a soil test to ensure you're feeding your lawn the right nutrients at the correct amounts.

Watering should be done only as needed to prevent drought stress. When you do apply irrigation, do it deep and infrequent instead of watering every day. It is a common mistake for homeowners to set their irrigation system on a schedule and forget about it. Remember, fungi love water and if you over water, you're giving the advantage to the fungi, not the turfgrass. The ideal time to water your lawn is in the early morning hours before sunrise. Irrigating during late afternoon or early evening is the worst thing you can do because this extends the leaf wetness period, however brown patch will love you for it!

Need help knowing when and how much to water your lawn? Try out our online water management tool at the following link: http://turf-ims.ncsu.edu/.

For more information about brown patch, including control recommendations, please visit the following link: http://www.turffiles.ncsu.edu/Diseases/Brown_Patch.aspx.

Be sure to check out other posts from NC State Turf Pathology (http://ncstateturfpathology.blogspot.com/).





For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Saturday, June 23, 2012

Pest News for Week of June 25th



ORNAMENTALS AND TURF
From: Steve Frank, Extension Entomologist

Twospotted Spider Mites Abound!

Things are heating up and the twospotted spider mite, Tetranychus urticae, thrives in hot dry weather. I have found many spider mites in the landscape on roses and many other plants. It is important to scout for twospotted spider mites now because they reproduce most rapidly in hot dry weather. Under these conditions they can mature from egg to reproducing adult in 5 days! Nursery crops are especially susceptible because they may be exposed to more sun than landscape plants and receive more pesticides. Twospotted spider mites feed on over 100 plant species sucking the fluid out of leaf cells. This ‘stippling’ damage can rapidly cause entire plants to take on a bronzed appearance. Look on the underside of leaves on susceptible hosts or beat foliage on a white piece of paper to scout for spider mites. If you notice mites or damage a range of control options are available the best of which are several new miticides that provide long residuals and efficacy against all mite life stages. Broad spectrum insecticide will make mite populations worse by killing natural enemies. For more information and product suggestions visit the newly revised insect note at
http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note25/note25.html.


Where Have All the Japanese Beetles Gone?

It is late June and so far I have not seen any Japanese beetles. I have a couple reports from around North Carolina and even reports that they are emerging in Maryland. So I guess they are trickling out but populations seem to have gotten lower and lower in the past several years. For three years in a row we have had severe droughts during the time Japanese beetles are ovipositing. They need moist soil so their eggs do not dehydrate and so tiny young larvae can borrow into the soil. Droughts have restricted successful reproduction to only well irrigated areas.

So keep an eye out and remember a few key things. Japanese beetle traps do not offer any protection to landscape plants and may actually attract more beetles on to your property so hang them in your neighbor’s yard. Likewise, treating a lawn for Japanese beetles grubs will not reduce defoliation of plants on that property since beetles fly in from great distances. Long-term protection for landscape and nursery plants can be achieved a neonicotinoid insecticide such as imidacloprid (e.g., Merit, Marathon II) or acetamiprid (Tri-Star). A new product with extremely low vertebrate toxicity but good efficacy for a number of pests including Japanese beetles is Acelepryn (chlorantraniliprole). For more information on the biology and management of adult Japanese beetles in nurseries and landscapes consult the insect note at http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note147/note147.html.

Please note-  Japanese beetles have been flying around for 2-3 weeks here in WNC, so applications of insecticides to control the grubs should be applied in early July on most high quality turf.  


Ugly Nest Caterpillars

Ugly nest caterpillars, Archips cerasivorana, are small green caterpillars that build webbed nests in cherry trees and a range of other plants. They are not particularly damaging to trees but attract a lot of negative attention with their ugly nests. The best option for these guys is to just prune out the nest. Even if you spray them you will still have to prune out the nest so it doesn’t look ugly so it is best to save a step.




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Saturday, June 16, 2012

Pest News for Week of June 18th


ORNAMENTALS AND TURF
From: Steve Frank, Extension Entomologist

Time to Target Bagworms

Bagworms have hatched and are still quite small. They can be difficult to find although they have constructed tiny bags that can be seen on leaves and needles of infested plants. It is easier to look for the large bags left from last year’s bagworm adults. These will be empty but are a good indication that small bagworms are likely roaming a plant. This is because female bagworms are flightless and overwinter and lay eggs in their bags on trees and shrubs. Thus baby bagworms hatch and grow up on the same plant as their mother was on the previous year.

Early in the year the before eggs hatch bags can be hand-picked from bushes with light infestations. Now caterpillars are still small and have not yet eaten much of your plant. Damage increases dramatically as caterpillars grow and they will easily defoliate branches. Small caterpillars are also much easier to kill than large ones. This is because they have less body mass to dilute toxins and their protective bags are not as thick. Therefore less toxic chemicals such as Bt formulations can be very effective when targeting small caterpillars. Other chemical options that are considered compatible with natural enemies are Acelepryn, TriStar, and spinosad. More information can be found at http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/ort081e/ort081e.htm.
   

From: Adam Dale, Department of Entomology, and Steve Frank, Extension Entomologist

Maple Spider Mites Active on Nursery and Street Trees

Maple spider mites (Oligonychus aceris) are common and damaging pests of maple trees throughout the Eastern United States. These spider mites overwinter on the trunk and branches of maple trees and migrate to the underside of leaves in the spring. Once there, they use their mouthparts to tear into leaf tissue and feed on cell sap, causing fine flecking or browning of the leaf. Maple spider mites have multiple generations per year which enables them to become quite abundant during a single season. These pests are a more serious problem in nurseries due to the close proximity of potted trees and applications of broad spectrum insecticides like permethrin. Studies have shown that over-application of permethrin can wipe out natural enemies and result in secondary maple spider mite outbreaks. However, they are still an issue on landscape trees around Raleigh. The first red maple that I sampled from in Cameron Village had a severe abundance of maple spider mites and the effects were obvious. The use of a hand lens or stereo microscope is necessary for correct identification of these mites but damage is a good indicator of infestation. They are dark brown or red with hairs along their backs and have eight legs while some immature forms exhibit green coloration and have six legs. Red eggs of these mites can be found on tree limbs and yellow or clear eggs can be found on leaf surfaces. Treatment for these pests includes foliar applications of acaricides. It has been observed that maple spider mites are more successful on trees in warmer temperatures. We are currently researching the effects that elevated temperatures have on maple spider mite biology and their natural enemies to uncover the mechanisms that are behind this. For more information on general spider mite management, please visit http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note25/note25.html.


Debris-carrying Green Lacewing Larvae are Active and Everywhere!

Green lacewing larvae are common predators of several soft-bodied pest arthropods across the United States. Their prey includes but is not limited to: scale insects, spider mites, aphids, thrips, and eggs of pest insects. They are useful in biological control because of their generalist and voracious feeding habits. Lacewing larvae are often compared to alligators due to their elongate, slender body shape and are typically yellow and brown in color with six legs. These larvae have large pincer mouthparts that they use to penetrate bodies of prey, paralyze them, and literally suck out their insides. They use these mouthparts to devour several hundred prey per week. Lacewings are known to be cannibalistic if they cannot find any other food source. This is one reason that they deposit their eggs individually on long hairs that suspend them above the leaf surface out of reach. These eggs are common and can be easily found on leaf surfaces.

Some but not all green lacewing larvae develop a camouflage cover which hides them from predation by other insects.  These are called debris-carrying lacewing larvae because they pick up plant tissue debris and other insect debris and attach it to their back. This camouflage makes them difficult to recognize by natural enemies and the inexperienced human eye. Often times they will appear to be a cluster of tree lichen until you notice small legs underneath or it start to move. They can currently be found on most plants just by scanning leaf surfaces. I have seen several recently without looking for them. These insects remain larvae for two to four weeks at which point they develop into winged green lacewing adults. Adult lacewings are not predators and primarily feed on plant nectar. The adults are commonly attracted to lights at night and can often be found around your home.


From: Kelly Ivors, Extension Plant Pathologist

Impatiens Downy Mildew Detected in Multiple Landscape Locations in North Carolina

Downy mildew of impatiens is caused by the ‘fungus-like’ organism Plasmopara obducens. The group of organisms that cause downy mildew diseases are not true fungi - they are more closely related to the well-known plant pathogens Phytophthora and Pythium than they are to true fungi. This is an important distinction to understand because many of the traditional fungicides used to control fungal diseases of plants do not have efficacy against the downy mildews. All types of propagated Impatiens walleriana, including double impatiens and mini-impatiens, and any I. walleriana interspecific hybrids, such as Fusion® impatiens, are susceptible to downy mildew; however, all New Guinea impatiens (I. hawkeri) and interspecific hybrids such as SunPatiens® are tolerant to downy mildew. No other bedding plants are known hosts of this particular downy mildew, although there are a few other downy mildew species that attack other floriculture plants like coleus and basil.

What does downy mildew look like?

A really good resource about identifying the disease, as well as disease control information, can be found at http://e-gro.org/pdf/Bulletin_1-8_Impatiens_Downy_Mildew.pdf.

In addition, a webinar presented by Dr. Colleen Warfield of Ball Horticultural Inc. can be found at http://go.ncsu.edu/impatiens_downy_mildew_webinar.

Downy mildew likes cool, wet/humid environmental conditions. The current conditions we’ve experienced recently across the state of North Carolina are conducive for this disease. The important thing to remember is that downy mildew is spread by wind currents, water splash or by the movement of infected plants. We know that the disease is now in our area and that the spores of the pathogen have the ability to spread long distances in air currents. Be on the look-out for it! So far it has been confirmed in both the western and Piedmont areas of North Carolina.

Fungicide treatments are not recommended for plants in the landscape; instead, all infected impatiens should be pulled from the landscape and destroyed. Fungicides are not always 100% effective at eliminating the disease. Allowing infected plants to remain in the landscape may allow the pathogen to overwinter as resting structures (called oospores), which can start a new epidemic later in the year or in following years if impatiens are replanted in the area. New Guinea impatiens, coleus, begonia, or other available bedding plants are safe to reset in the affected area.


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Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina State University, North Carolina A&T State University or North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact an agent of North Carolina Cooperative Extension.



For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Saturday, June 2, 2012

Pest News for Week of June 4th


ORNAMENTALS AND TURF

From: Steve Frank, Extension Entomologist

Red Headed Flea Beetles in the Nursery

Flea beetles have been an increasing problem in nurseries and landscape in the past couple years. We do not know the reasons why but clinic reports have increased as well as phone calls and other reports from growers. The red-headed flea beetle has been the main culprit attacking roses, hydrangeas, and other nursery crops. The adults are small (2 to 4 mm) and black or iridescent and feed on leaves. Larvae feed on plant roots and are small and cream-colored. Their most notable feature is how hard they are to catch when you want to submit a sample to the North Carolina State University Plant Disease and Insect Clinic. As their name implies they are very good jumpers. Feeding by these beetles produces shot holes in leaves though heavy infestations can skeletonize leaves.

Flea beetles are active now as adults and larvae. They are more likely to cause aesthetic or economic damage in nurseries where many plants are grown in close quarters. In that case, treatment is needed. Available chemicals include spinosad (Conserve), imidacloprid (Merit, Marathon), thiamethoxam (Flagship) and acephate (Orthene).




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.