Friday, May 28, 2010

Nematode Sampling in Blackberries

Blackberry production in Henderson County is really gaining ground. Currently we have about 85 acres of blackberries in production. Because this is a new crop for the area (some of our plantings will be harvesting for the first time this season) we are busy learning the ins and outs of blackberries.

Last year, Dr. Zvezdana Pesic-VanEsbroeck (I just call her Dr. Z), who is the director of the Micropropagation Unit at NCSU, came to the county to assess the presence of virus diseases on blackberries. We found virus in every one of our fields to some extent. Below I have posted some pictures of virus disease symptoms on blackberry.

There are many viruses that affect blackberries, some haven't been identified and described yet. Virologists are unsure how some of these viruses are transmitted to blackberries.

We do know that some of these viruses are spread by plant parasitic nematodes, microscopic worms that feed on plant roots. As a result, it is important to take soil samples prior to planting in order to determine levels of plant parasitic nematodes.

We are specifically concerned with a nematode known as Xiphenema, the dagger nematode. Xiphenema is known to transmit the nepoviruses, tomato ringspot virus, tobacco ringspot virus and grapevine fan leaf virus (a devastating disease in vineyards). Xipehema is also known to be a problem in newly planted apple orchards.

Last year a blackberry grower in Henderson County noticed mottled leaves and mishapen berries. Concerned that it might be a virus, he sent it to four different labs across the U.S. Each test came back with the same result, tobacco ringspot virus.

Symptomatic leaf and blackberries caused by tobacco ringspot virus.

Close-up of mishapen blackberry fruit caused by tobacco ringspot virus.

Concerned with dramatically reduced yields and unmarketable berries, the grower has decided to either replant the field in blackberries or to chose a different crop. The first thing we need to do to decide if blackberries should be replanted in the field was to determine the nematode levels in the soil. This is also an important step to help us determine if the virus developed in the field or came in with the plants.

So, I got my nematode/soil samling supplies together. A clean bucket, soil probe, nematode sample boxes from the NCDA&CS, quart plastic bags, a permanent marker, pen and notebook (not shown).

Nematode sampling supplies.

The grower has two fields, one where the virus problem has been identified and one that appears healthy. Both fields were once in apple production. The problem field is in a lower site and all the plants came from one particular nursery. The healthy field is slightly uphill from the problem field and the plants here came from another nursery. The plants in the healthy field were planted a few months later than the problem field.

Problem field. Notice the sporadic growth and stunted plants.

Plants in the healthy field. Notice uniform growth of the blackberries.

In taking the nematode samples, I made sure to sample both the healthy field and the problem field. I took samples from the healthy field first, making sure not to contaminate it with soil or nematodes from the problem field.

I took 20-25 soil and root cores from the beds. The samples were taken from 8-10 inches. Because Xiphenema is usually found in the root zone soil (they are migratory ectoparasites, meaning they move from root to root piercing them to feed), I took the samples as close to the plant and drip-line as possible. This required some major work getting into that dense plant canopy. I took samples throughout the planting, making sure to get a representative collection.

Next, I took 20-25 cores from the problem field. Again taking samples close to the plant and drip-line. For this site, I made sure to take the samples from symptomatic plants.

Soil for the nematode assay. Note the nematode sample boxes from NCDA.

I am anticipating the results from the nematode test. If it comes back with levels of Xiphenema that are high, the grower has a few options.
  1. Plant a different crop in this site for a few years (Xiphenema reproduces once per year and can live four to five years) before replanting in blackberries. Brassica crops are a good option. They are known to have some properties that may decrease the levels of plant parasitic nematodes.
  2. Plant this site in a new crop entirely. Xiphenema has a wide host range, which includes perennial orchards, grapes, strawberries, grasses, forest trees (spruce, pine) and even some weeds. I am having a hard time finding crops it doesn't do damage.
  3. Use a fumigant to treat the land prior to planting. Fumigants labeled for blackberry nematode control are metam sodium and telone. These need special equipment for application and may have an 8 week pre-plant interval. Refer to the NC Ag Chem Manual for more details.
In addition to taking nematode samples before planting blacberries and preparing your soil for planting, it is very important to purchase tissue culture plants. Ask the nursery if the plants are true tissue culture and not cutting from tissue culture plants. This will help to make sure you are not bringing diseased plants into your field (which is very important for a perennial crop like blackberries).

For more details on nematode sampling, visit the NCDA&CS site.
Your local Cooperative Extension office can provide the test boxes and assistance.

Thursday, May 20, 2010

Downy Mildew on Hops Present in WNC

This week I have been visiting with our WNC hops growers. To my dismay, I found the dreaded downy mildew, Pseduoperonospora humuli, in two of the yards.

We saw the beginnings of this problem late last season on the hop cones. See my post from September 2008 on downy mildew of hops.

When determining if you have downy mildew in your hops yard, look for pale green to yellow newly emerged spikes that appear stunted.

Note the pale green, stunted spikes of this hops plant.

A closer look at the pale green to yellow new spike. Note the shorten internodes and miniature leaves.

Another shot of the infected, newly emerged shoot. Take note of the curled and brown lower leaves.

A close up of the browning, curled leaves on the hops shoot. The leaf looks dirty, but those are actually millions of downy mildew sporangia!

A hops leaf exhibiting foliar symptoms of downy mildew.

The underside of the downy mildew infected leaf. Note the fuzzy spores.

The worst downy mildew infection that I noted was on 'Nugget'. 'Nugget' is considered to be susceptible to downy mildew. Interestingly, in the hops yard where downy mildew was found on 'Nugget', it appeared to be the most vigorous variety.
**Update May 21**
Some sources report that 'Nugget' is resistant to downy mildew, while others report it is susceptible.

Downy mildew was also found to be prevalent on 'Centennial' which is considered to be tolerant to downy mildew.

One of the best management strategies for the control of downy mildew on hops is to remove primary basal spikes and to heavily prune and strip leaves. This is important in order to prevent downy mildew from moving up the bines and eventually infecting the cones. Pruning and thinning also helps to reduce moisture and humidity in the lower part of the canopy which is favorable for disease development.

Hops yard with lower leaves stripped up to 3 feet.

Because we are expecting wet weather in the next few days here in WNC, action needs to be taken quickly to prevent the spread of disease to other bines. The first step is to prune and thin the bines.

In addition, the application of fungicides is recommended as soon as the wet weather is over or before if product is rainfast. For a complete list of fungicides (conventional and organic) used to control downy mildew on hops, visit the Oregon State University Downy Mildew Fact Sheet. Before you apply any pesticide make sure you follow the specific label directions and make sure that the product is labeled for downy mildew on hops in NC.


Organic Fungicides Labeled for Management of Downy Mildew of Hops in NC:
  • Sporatec (rosemary oil, clove oil and thyme oil)
  • Copper products (look for OMRI label)
  • Sonata (Bacillus pumulis strain QST 2808)

Conventional Fungicides Labeled for Management of Downy Mildew of Hops in NC (not a complete list):
  • Curzate (cymoxanil) - must be tank mixed with a fungicide of different mode of action, such as copper
  • Tanos (cymoxanil + famoxadone) - must be tank mixed with a fungicide of different mode of action, such as copper
  • Acrobat and Forum (dimethomorph) - must be tank mixed with a fungicide of different mode of action
  • Fosphite and other phosphorous acid products
  • Legion (Aluminum tris)

The best approach would be to incorporate a few of these products in order to slow down the possibility of fungicide resistance. Again, always follow the directions on the label - it's the law!

Hops Pest: Eastern Comma Butterfly

A few weeks ago a number of our local hops producers were noticing large holes in some of their hops leaves. Upon closer inspection, they found spiky, white caterpillars feeding on the leaves.

Larva of Eastern comma butterfly found on hops in WNC (picture courtesy of R. Pelczar).

The entomologists at NCSU agreed that the caterpillars are larvae of the Eastern comma butterfly, Polygonia comma.

Larva of Eastern comma butterfly found on hops in WNC (picture courtesy of R. Pelczar).

Hosts plants of the Eastern comma butterfly are American elms, hackberry, nettles, false nettles and other members of the Urticacea. But, perhaps the favorite food of the Eastern comma butterfly is hops.

Beginning in the early 1900's, the Eastern comma butterfly was referred to as the "hop merchant" because hops farmers would predict the future price of hops based on the variation in the silver and gold spots on the pupae.

The larvae ranges in color from white to green-brown to black and are typically just over 1 inch long. The spikes also range in color from black to white with black tips. The larvae rest on the underside of leaves and make nests by silking together the sides of the leaf. The larvae rest during the day and feed at night.

Eastern comma butterfly larva. (Picture courtesy of Echoview Farm).

The eggs are green with vertical ridges and are laid singly or in stacks. I was lucky to find these (sorry they are not the greatest pics)!

Eggs of Eastern comma butterfly on underside of hops leaf.

Close-up of the eggs of Eastern comma butterfly. Notice the vertical ridges.

Pupae are variable in color but always have prominent ventral gold or silver spots.

The adult is an orange and brown butterfly with a wingspan of 1.75 to 2 inches. With its wings folded it looks like a dead leaf.

Life Cycle:
There are two generations per year for Eastern comma butterflies. During the summer, the new butterflies are inactive during the hot period and then become active again in the fall. The fall brood of adult butterflies overwinter and start the cycle again in the spring.

The feeding damage caused by the Eastern comma butterfly larvae ranged in the individual hops yards here in WNC. One grower experienced quite a bit of initial damage, but was able to prevent further destruction by hand-picking the caterpillars.

Growers at another farm reported shaking the bines to knock off the caterpillars and then destroying them. This appeared to work well and little damage has since been noted. This grower also applied BT (Bacillus thuringiensis, a bacterial biological control material that is labeled for Lepidopteran pests) and reported that it was effective.

Hopefully, the Eastern comma butterfly will not be a problem for our hops growers in the future. At least now we know what the pest is and how to control it.

Thanks to all the folks who helped in the identification of the larvae and for the great growers for sharing their experience and their wonderful pictures!

To learn more, read the University of Florida's fact sheet on the Eastern Comma Butterfly.

Sunday, May 16, 2010

Local Hops Producers Featured in Raleigh N&O

Congratulations to two of our local WNC hops producers, Julie Jensen and Van Burnette, who were featured in the Raleigh News & Observer Story "Brewers Have High Hopes for NC Hops".

In addition, we have a lot to be thankful for with all the hard work that NCSU researchers, Dr. Jeanine Davis, Dr. Deanna Osmond and Rob Austin are doing to help our hops industry grow!

Congratulations everyone!

Here is a sidebar from the on-line article entitled, "Beer in the Mountains":

The four farms working with N.C. State University to explore the possibility of commercial hops growing are all clustered around Asheville, and that's no coincidence: The mountain city is gaining national attention as an attraction for craft-beer lovers, and would be an obvious market for the bitter flowers.

Last year Asheville was voted "Beer City USA" in an online poll, sharing the top honor with a much better-known brewing city, Portland, Ore.

Also in 2009, eight brewing operations in the city and four nearby formed the Asheville Brewers Alliance.

"Any day of the week, you can have your choice of probably 80 Asheville-made beers," said Tony Kiss, who covers beer like a sport for the Asheville Citizen-Times.

A tour called the Brews Cruise takes tourists on a circuit of local brewing operations and the city now boasts five annual beer festivals. All 3,500 tickets for the fall Brewgrass Festival were snapped up in less than a day when they went on sale Wednesday.

With all this beer action, Black Mountain farmer Van Burnette said hops growers like him not only could supply local brewers with their most crucial ingredient, but also could become part of a critical mass of attractions for the beer-related tourism.

Wednesday, May 12, 2010

Blackberry Rusts

I have been spending a lot of time lately in the blackberry fields of Henderson County. This is a really great crop to work with and our growers are excellent. It is a relatively new crop for the county, but over the past few years our growers have planted about 87 acres of blackberries. Most of the varieties that we are cultivating are floricane-fruiting varieties developed from the Arkansas breeding program, including Natchez, Navaho and Ouachita.

One of the things we are learning is all of the disease and insect issues that we are going to experience. I have observed two rust diseases on blackberries so far this season and would advise all growers to be scouting for these problems.

Section of Natchez planting with an obvious problem.

The first disease I observed was causing a problem only in Natchez. It is cane and leaf rust. The infected section of plants had some rust problems late last season. The grower has heavily pruned out infected canes and applied products for management.

The causal agent of cane and leaf rust is the fungus Kuehneola uredinis. Cane and leaf rust is first seen in late spring on infect floricanes. The large yellow-orange spores of the pathogen split the bark. At this point, we have not observed any rust on the leaves.

Vibrant yellow rust spores emerging from cracked bark.

Bark cracking in multiple spots on Natchez cane, exposing rust spores.

Pustule of K. uredinis breaking the bark on Natchez.

Control of cane and leaf rust involves cultural and chemical control. The first step is to remove heavily diseased canes and dispose of them in order to reduce inoculum (spores). Highly susceptible varieties or areas with a history of this problem require chemical control. Products used to control cane and leaf rust are copper, myclobutanil (Rally), pyraclostrobin (Cabrio) and pyraclostrobin + boscalid (Pristine).

Next rust problem...

At first glance there is no problem with these Navaho blackberries, right?

Upon closer inspection, there is an obvious orangey problem. The leaves are also slightly yellowish.

Notice the orange pustules on the underside of the leaves. The leaves also appear pale green.

This problem is orange rust on the variety Navaho. Orange Rust is the most important rust problem in the eastern United States and a limiting factor in the northeast. It is a systemic rust, meaning that it lives throughout the infected plant.

Symptoms of orange rust can be seen in the spring as new growth appears. The young shoots are spindly and the new leaves are often mishapen, stunted and pale green to yellowish. The first spot on the leaves will be a subtle black speck on the upper leaf surface that is caused by the mycleium of the pathogen growing in leaf tissues. In a few weeks, the orange rust spores can be seen on the bottom of the leaf surface.

The infected leaves are stunted, have a slightly yellow hue and the ends are curled.

Close up of the orange-blister like aecia and many orange aeciospores [Aecia = Geek talk for a cuplike structure containing the rust spores (aeciospores)].

There are two forms of orange rust. The form on black raspberry is caused by a fungus known as Arthuriomyces peckianus, while the form more common on blackberry is known as Gymnoconia nitens. Orange rust is not known to kill plants, but it causes reduction in vegetative growth and fruit production. Infected plants rarely recover.

Navaho is susceptible to orange rust. Orange rust has not been observed on Natchez or Ouachita and is seldom a problem on Chester or Hull in North Carolina. Orange rust can also be observed on our wild caneberries. Cornell University has a good factsheet on orange rust.

Control of orange rust includes picking resistant varieties, removing heavily infected canes and plants and applying fungicides. Fungicides (Rally, Pristine or Cabrio) are applied in the spring before pustules are formed on the lower leaf surface. Often the wild blackberries are used as indicators of when to spray. Sprays are applied on 10- to 14- day intervals until the mean temperature remains above 77 degrees F.

I do not have specific organic recommendations available for either of these disease, but the use of resistant varieties, removal of diseased plants (including wild brambles if possible) and diligent scouting will do a lot of good. In addition, here is a great ATTRA publication on the Organic Culture of Brambles.

Monday, May 3, 2010

Henderson County Father and Son Team Featured in Times-News

I would like to take this opportunity to congratulate some local growers.

Stepp's Plants, etc. is a great local farm in Henderson County that is run by father and son team Larry Stepp Sr. and Larry Stepp Jr. The pair have a great dynamic and it is a joy to talk and learn with them. The Stepps grow a wide variety of small fruits, asparagus, diverse vegetables, bedding plants and hanging baskets.

Recently, the duo was featured in the Hendersonville Times-News. They even shot a video (below).

To read the entire article, visit "Son Leaves Corporate World to Join Dad in a New Farming Venture".

You can find Stepp's Plants, etc on Facebook.
Visit Stepp's Plants, etc! Stepp's Plants, etc and other local farms will be part of ASAP's Family Farm Tour on June 26 and 27!