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There are some plant diseases caused by fungal, bacterial and viral pathogens that can be seed-borne. Growers should consult seed guides to determine for which type of plants saving seed is recommended.  If plants had symptoms of a plant disease last year, the disease should have been identified to determine if the pathogen could be transmitted in or on the seed.  When contaminated seed is planted the following year, the new plant is vulnerable to infection from the pathogen.   Seed should only be saved from healthy plants or purchased from reputable seed dealers.

Seed companies often apply fungicides to protect seeds. Although these treatments give some protection against pathogens in the soil that attack germinating seed and emerging seedlings, they do not control pathogens that may attack the plant after the seedling stage.  Typically, seed treatments protect the young plant for only a couple weeks, and only against specific soil-borne seed rots and seedling blight-type pathogens.  Seed treatments do not provide season-long protection.

Growers should examine transplants carefully before purchasing as diseases coming in on transplants is arguably the most common method of introducing a pathogen into the home garden.  A disease such as bacterial spot on tomato and pepper is often introduced into the garden via infected transplants.  Select healthy transplants that appear disease-free with no visible signs of leaf spots or blights.

Planting disease-resistant varieties is the most effective and economical way to control plant diseases.  Purchase disease-resistant varieties when available and when they address the most common diseases in your area.  A variety listed as having disease resistance means it is resistant to one or more diseases, however, it does not mean it is resistant to all plant diseases.  Seed catalogs generally list the resistant traits of vegetable varieties that they offer growers.

In Alabama some of the more popular crops and associated disease resistant traits are listed below with their seed catalog abbreviations listed:

  • Tomatoes: Fusarium wilt (F2, F3), Root-knot nematode (N); Early blight (AB); and Late blight (LB).

 

  • Squash/Cucumbers: Powdery mildew (PM); downy mildew (DM); anthracnose (A); scab (S); and multiple plant virus diseases (WMV, ZMV, CMV, PRSV).

     
  • Beans: Bean mosaic virus (BMV), anthracnose (A).

Planting dates can be an effective tool for disease management. Follow the recommended planting dates for the particular vegetable being grown in your area of the state.  Planting into cool, wet soils can often lead to an increase in seed rots and seedling blights. Planting later in the season may expose plants to diseases and insects that are more common during the warmer months of the year. 

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Edward J. Sikora 

Extension Plant Pathologist



The Southeastern Blueberry bee, Hapropoda laboriosa, is a common native solitary bee that is most often seen working blueberry flowers. As the name implies, blueberries are one of its preferred forage plants but it can also seen working redbud, Carolina jessamine, wild blueberries and other members of the Ericaceae family. The bee has one generation per year but one individual bee can visit as many as 50,000 blueberry flowers. This bee works blueberry flowers by "sonicating" or buzzing when it lands on a flower. This activity shakes pollen down onto the bee's abdomen where it collects it. The nesting habit of the bee is not clearly understood but natural woodland habitat should be preserved near blueberry plantings.

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Doug ChapmanRegional Ext. Agent

 


If you spotted our last post, you already know that our Spring hasn't merely sprung, it's a bear-trap whose steely jaws are clapped shut on your colonies. As a result, colony build-up is off and running because of the early nectar flows. So far we've advised you to consider feeding your bees to ensure that they don't starve. Now we urge you to carefully keep an eye out for a particularly menacing creature.

Along with buildup of your bee population, and especially with those first batches of drones for spring breeding, come the Bee Ticks. If you are new to beekeeping, you may not be aware of these creatures. Just imagine something roughly the size of a Chihuahua biting your body to drink your blood. Wouldn't take long for you to feel, um, drained.

This bee tick is more commonly known as the Varroa mite (Fig. 1). It's scientific name – Varroa destructor – gives you an idea of its power over your honey bees. Unfortunately, we humans, by shipping around our honey bees over the last half century, have spread the Varroa mite from its home in East Asia to nearly every corner of our globe. The very few exceptions include the island of Newfoundland in Canada, the Isle of Man in the UK, and interestingly, all of Australia (there are a few other locations too). It arrived in the United States in the mid to late 1980s, and has since spread to every state.

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Figure 1. A female Varroa mite on a newly emerged worker honey bee (denoted by a green arrow). Photo by G. Williams.

Varroa mites are arguably among the most important parasites of honey bees that we know of. They damage your colony by feeding on bee blood (we bug folk call it hemolymph). Not satisfied with the blood of developing larvae and pupae (Fig. 2), they also feed on adults.



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Figure 2. Female Varroa mites within drone pupae cells (denoted by green arrows). Photo by W. Rowe.

Being drained of blood weakens bees, shortens their lives, and makes them more susceptible to disease. Speaking of disease, have we mentioned that the Varroa mite is a handy carrier of bee viruses? When they're feeding on bee blood, they are, all mosquito-like, contaminating your bees with viral diseases. One of the most common signs of a high mite population is the presence of adult bees with deformed wings (Fig. 3). This is typically caused by Deformed wing virus, and likely means that it is already really late to be controlling for Varroa mites in your colonies.

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Figure 3. A dead experimental honey bee worker exhibiting signs of deformed wings, most likely because of concurrent Deformed wing virus infection and Varroa infestation. Photo by G. Williams.

You just might be crying at this point in our happy documentation of what seems like a bee vampire movie. Yes, Varroa mites can be death for your colony. In fact, they are a major cause of most colony losses. Unless…

You Begin An Integrated Pest Management Program For Mites Right Now!

We just used some words, there. It's not something you have to purchase, per se. Simply put, it's a holistic approach to managing pests in your colonies by employing appropriate monitoring and treatment regimes, the latter of which includes using biological, cultural, physical, and chemical tools at appropriate times. And by 'control' we mean just suppressing their numbers. It is nigh impossible to keep bees in Alabama without experiencing Varroa mites at some point or another.

There are several methods for checking up on your mite population, and each brings its own pros and cons. We most often recommend the sugar shake or wash methods. Essentially, you can use powdered sugar or a fluid (either rubbing alcohol or winter windshield washer fluid) to dislodge mites from about 300 adult bees collected from the broodnest. Counting the number of fallen mites, coupled with some simple mathematics, will allow you to determine the percentage of mites that are infesting adult bees in your colony. Levels can vary depending upon the surrounding environment and time of year, but generally anything greater than a 3 % infestation level warrants further investigation immediately. For those of you with fewer than 10 colonies, make sure you check each of them. For those of you with more, try to get to as many as you can reasonably manage! You'll want to do this at least 4 times throughout the year.

The most common method for controlling the Varroa mite when threshold levels have been exceeded is by using a miticide. There are currently 10 products approved for use by the EPA; each has its own unique properties and directions for use (Table 1). Remember, the label is the law! Make sure you stick to it!

Table 1. Current pesticide products registered by the EPA for use against Varroa mites in honey bee hives. Modified from the EPA. Some products may only be available under specific circumstances (e.g. emergency-use permits). Consult the EPA for up-to-date recommendations.

ProductActive ingredient
ApistanFluvalinate (10.25%)
For-MiteFormic acid (65.9%)
Sucrose OctanoateSucrose octanoate (40%)
Api Life VarThymol (74.09%), Oil of eucalyptus (16%), Menthol (3.73%)
MiteAway Quick StripFormic acid (46.7%)
ApiguardThymol (25%)
HopGuard IIHop beta acids resin (16%)
ApivarAmitraz (3.33%)
Oxalic acid dihydrateOxalic acid (97%)
CheckmiteCoumaphos (10%)

But it's Spring and you want to get that fine honey. If you don't stop the mites that spring honey might be the last you get. What to do, what to do…

Well, there are some registered mite products that you can use while the colony builds and starts storing honey as spring unfolds. These are mostly 'natural' treatments – Formic Acid and Hops Acids. Formic Acid is made by insects and can already be present in the hive. Hops Acids (Lupulone, Colupulone, Adlupulone) disperse quickly and break down in the hive environment without contaminating your honey.

There are a few formulations of Formic Acid available for use. That said, only 1 product is labeled for spring use while honey supers are on the hive:

  • MAQS (Mite Away Quick Strips), manufactured by Nature's Own Design Apiary Products Inc. of Ontario, Canada, is labeled with the EPA as being safe for use while honey supers are on the hive. Formic Acid products like MAQS are known to cause brood death and can only be used when temperatures are between 50oF (10oC) and 85oF (29.5oC).  If you decide to use MAQS, be certain you read the product's entire label and understand the directions.

There is only one commonly sold product for Hops Acids:

  • HopGuard II, manufactured by BetaTech Hop Products, a subsidiary of Barth Haas Group Inc., is labeled with the EPA as being safe for use while honey supers are on the hive. The treatment is applied to the brood chamber(s), and make sure you don't collect honey or wax from the brood chamber after treatment. This product is best used before the queen starts her egg laying in the spring, but can still be used afterwards. HopGuard II does not have the narrow temperature range that MAQS does. However, warm weather can quickly dry the treatment strips, thereby reducing its efficacy. If you decide to use HopGuard II, be certain you read the product's entire label and understand the directions.

With a bit of luck, and a lot of careful planning, you can keep mite levels below treatment thresholds for most of the year by incorporating physical and cultural practices like drone brood removal (Fig. 4), screen bottom boards, brood interruption, and use of hygienic stock into your Varroa IPM scheme. When it comes time to treat using chemicals, don't be a one-trick pony! You'll only be breeding for resistant mites!

Fig. 4. Honey bee drone brood frame.jpgFigure 4. A plastic drone frame being inspected for Varroa mites. Once cells are sealed, drone frames can be removed from colonies to help reduce mite population levels. Photo by G. Williams.

Further readings

Orginally available on auburnbees.

So, in case you've not been outside for the last 2 months, you've noticed that Winter in Alabama was held in the first full week of January. After putting in that week of work, it snuck off the job and Spring had to be called in early by The Management. We are now, in fact, 20 days ahead of last year in temperatures and plant activity (Fig. 1).

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Figure 1. Map illustrating the timing of spring leaf emergence, as of February 1, 2017, across the continental United States. It highlights that Alabama is approximately 20 days earlier than historic records (1981-2010 annual averages). Map from the US National Phenology Network (www.usanpn.org).

Far warmer than normal temperatures have helped honey bee colonies overwinter better and have likely spurred your colonies to start ramping up to springtime strength. Yay! But, the January freeze killed off most of the winter blooming plants, and perhaps the varroa mite wasn't knocked down quite as much as in previous years. Oh no!

Spring build-up is important. This is when the queen's egg-laying goes into overdrive. Soon a fast buildup of new workers ensues. These new bees then act as nurses that assist in the rearing of yet more bees, while the nurse bees of winter past move out to forage on spring flowers. If all goes well the whole cycle keeps repeating and we get loads of honey come June!

In a year like this one, that bad week of winter has knocked out much of our winter forage, such as Yellow Rocket (yellow flowered relatives of radishes) or Shepherd's Purse (Capsella species). That means the bees have been living on stores for most of January and February. Recently, the maples have bloomed and that's a boost for our bees (and a pain in our sinuses). Unfortunately, this forage is likely not enough to support high levels of brood production in preparation for spring.

Even if you see active foragers bringing resources to your colonies, we recommend that you consider feeding your bees now, especially if your colonies are light. On a warm afternoon, you can quickly check reserve levels by inspecting peripheral honey frames or by hefting – whereby you lift one side of the colony to judge its weight. You can practice this by using an empty hive filled with a known amount of materials, like large rocks!

Nowadays your colony should contain at least 40 lbs of stored honey. Given our one-off winter and over-early spring, we're betting your colonies won't weigh as much as you'd like.

Now that day-time temperatures are regularly hitting the 60s and 70s, the best way to get the necessary carbohydrates to your bees is to give them sugar syrup (1 part white granulated sugar to 1 part water) using a hive feeder (Fig. 2).

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Figure 2. Photograph of a beekeeper filling a hive top feeder with sugar syrup. Because this feeder does not prevent workers from entering the feeding compartment, straw acts as a float to minimize drowning. Photo by G. Williams.

Protein, which is vital to developing workers, can be fed via a pollen supplement (contains some bee-collected pollen) or pollen substitute (does not contain bee-collected pollen) placed right above the broodnest (Fig. 3). Several store-bought varieties exist, whereas countless home recipes prevail – nearly all are soy-based.


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Figure 3. Photograph of a commercial pollen substitute placed directly above the broodnest, as well as a beekeeper filling a division board feeder with sugar syrup. Photo by G. Williams.

Feeding sugar syrup and protein now will likely provide you with big benefits later. Insuring your colonies have well-fed and healthy populations now also provides you with opportunities to make increase via splits or nucs in March, April, and May!

Happy Beekeeping!





Further readings

  • Caron, D.M & Connor, L.J. 2013, 2nd Ed. Honey Bee Biology and Beekeeping. Kalamazoo, Michigan, Wicwas Press, 368 pp.
  • Dadant & Sons. 1978, 3rd Ed. The Hive and the Honey Bee. Carthage, Illinois, Dadant & Sons, 740 pp. (or any updated version).
  • Tew, J.E. 2001. Beekeeping Principles. Clarkson, Kentucky, Walter T. Kelley Co., 245 pp.

Posted on February 20, 2017 by auburnbees

William Rowe, Regional Extension Agent

Geoff Williams, Auburn University Department of Entomology & Plant Pathology

 


Have you ever given much thought to the vegetable seeds you plant? Why do you plant them? Taste? Production? Disease resistance? Recommended from a friend? Many people plant the same cultivars each year and never think of planting anything else. The Extension System has taught many tomato workshops over the years and have a tomato taste test as part of the program. Many gardeners bring in some of their favorite tomatoes. We assign the tomato a number, then slice it up for tasting. Participants eat the tomatoes, not even knowing which one they brought. It is very interesting to see the participants who have grown a particular tomato for years because they thought it was the best, only to actually like several others that they have never grown. There are actually thousands of different tomato cultivars to choose from, and I do not know if someone would ever eat fruit from all of them but they can certainly have fun trying.

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One question is where would someone find different tomato cultivars? Nurseries and farm supply stores have many cultivars ready for transplanting, and growing your own transplants is an option as well. Seed starting can be fun, and this opens the door to thousands of cultivars. The Extension System can help you if you have questions about growing transplants.

Tomato plants get several diseases that lower production, and cultivar selection could help decrease some of those diseases. Some of the common problems you can find resistance to include fusarium wilt and nematodes. However, resistance to verticillium wilt, alternaria stem canker, bacterial speck, gray leaf spot, tobacco mosaic wilt virus, and others are available. Tomato spotted wilt virus is common, and cultivars such as Bella Rosa, Amelia, BHN 640, Christa, Primo Red, and others are resistant. Growers can even find heat set tomatoes. Many tomatoes do not set fruit well with temperatures in the 90's. While tomatoes do not perform well with high temperatures, the heat set tomatoes do better than others. Some of the heat set tomato cultivars include Phoenix, Red Bounty, Redline, Solar Fire, and others. Some tomatoes are more suitable for greenhouse production or high tunnel production than others, and choosing the right cultivar for those locations is very important.

Just check the tags where you purchase plants or seeds, and it will list the plant resistance. Tomatoes are not the only crop in which you can find disease resistant cultivars. If you have questions about disease resistance, seed starting, or most anything else, just call your local Extension office for additional information.  


Podocarpus aphids were seen on … podocarpus.  They were seen on one plant blackened by old sooty mold.  The rest of the group was not affected.  Aphids and other honeydew producers can be detected by looking for shiny spots on leaves as in the picture. Looking for something that dropped that spot of honeydew usually yields aphids or other suspects.  Aphids in trees and tall shrubs will drop honeydew on cars.   

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Scale was seen on a fan palm.  Crawlers were seen, making this the perfect time to spray with an insectide.  This picture was taken with an Iphone set on a box of baking soda.  I like this setup because the box has three different heights on which to hold the camera. The image can then be enlarged before shooting the picture, and then enlarged even more when looking at it.  It's sort of like having a dissecting microscope that you can also use to call people and check Facebook.

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Frizzle top was seen on a number of sago palms.  This is caused by a manganese deficiency.  

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False oleander scale continues to be an entomological pain in the neck.  Timing is the key for this pest.  When the scale are young, as on the left, oil sprays will work well.  As they mature, they are harder to control.  The middle and right pictures show adults under the shells that were picked off with a pin.  This stage produces the yellow mush when you pinch the scale with your fingernail, indicating that it's still alive.  The picture on the right shows an adult with eggs, which will soon become crawlers.  A grower would need to wait for the crawlers to come out from under the shells to control them. 

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Albert Van Hoogmoed

Southern pea or cowpea (Vigna sp.) has many insect pest problems. Pest spectrum includes chewing insect pests like armyworms as well as the sucking insect pests like aphids and leaffooted bugs that we have frequently encountered in our research plots. The cowpea curculio (Chalcodermus aenus Boheman) is a unique insect problem in Alabama and Georgia, one that likes to feed on cowpeas and can cause severe destruction of the crop. 

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Conventional insecticides appear largely to be ineffective when used as the only means of control. Here we share our new experiences with the insect as the research continues to expand across Alabama. In 2015, research was located at the Wiregrass Research and Extension Center (Headland, AL) where the curculio is a well-established pest and insecticide resistance is a major issue. 

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As our past report suggests (see listing of related articles below), seed damage in untreated check ranged from 27 to 80 percent in the first year in untreated check plots. Treated plots (with weekly foliar insecticide application) seemed to have higher damage from the second generation of the pest, thereby completely ruining the produce. There were no significant differences between the treatments which was very frustrating, to say the least.

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In 2016, cowpea curculio research was expanded to include the Brewton Agricultural Research Unit (Brewton, AL) where we had never planted cowpeas before. This time we tested a range of pre-planting soil treatments along with foliar application of insecticides with the intention of targeting adults in soil as well as those getting on the plants. Results were unique, although none of the soil + foliar treatments significantly reduced seed damage. At this new location, the curculios were able to locate host plants quickly and caused 23 percent seed damage (average from four replications) in the untreated check plots within the first year. We are expecting a higher level of seed damage in 2017 when this test will be repeated at Brewton. As stated earlier, none of the soil and foliar insecticide applications were effective in stopping the onslaught of curculios during the peak activity period (July to August). We had the same study in replicated plots in Headland as well with similar nonsignifcant differences between untreated and treated plots.

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The point of this discussion is that producers wanting to grow cowpeas for the first time or expand current operations have a tough decision to make. An IPM plan that is based on cultural control and insecticides needs to be carefully put together. We are using nonregistered products for experiments and then destroying the produce – commercial farmers don't have that option. We strongly suggest you to take a look at the curculio webinar and video archived on the first link listed under 'Additional Information'Then get together with the authors or the nearest Commercial Horticulture Regional Extension Agent to develop your IPM plan before starting cowpea production or increasing acreage. Call 251-331-8416 (Dr. A) or email bugdoctor@auburn.edu. 

Overall cowpea curculio recommendations:

  • Start insecticide treatments two to three weeks ahead of flowering.
  • Mix PBO (synergist) with synthetic pyrethroids and rotate chemistries.
  • Spray frequently at 3-5 d intervals and follow the pesticide label.
  • Scout intensively before bloom and keep records!
  • Don't quit spraying insecticides too soon!

Additional information:

Ayanava Majumdar (Dr. A), Ext. Entomologist

Neil Kelly, Regional Extension Agent

Larry Wells, Wiregrass Research and Extension Center

Brad Miller, Brewton Agricultural Research Unit 


THRIPS

Thrips may delay maturity if heavy damage occurs at the 1 to 5th true leaf stage. Use seed treatments or insecticide applied in-furrow at planting. Make foliar spray when the first true leaf is just emerging if cotton is planted before May 10 and the minimum nighttime temperature is below 65⁰ F.

PLANT BUGS

Monitor cotton for pinhead square set when squaring begins (about 6th true leaf). Continue checking pinhead square set until about first bloom. During this same time period use sweep net (can be purchased for about $75 from Gempler's ,  www.Gempler's.com) to sample for adults. Spray for adults if 5-8 per 100 row feet (33 sweeps) are found.

PLANT BUGS

After first bloom check for immature plant bugs (small, green with long antenna) with a drop cloth spread between two rows. Beat plants briskly to dislodge immatures from inside of the square bracts. Spray at threshold of one immature per row foot. Continue surveys for about 3-4 weeks.

APHIDS          

Only treat when over 50% of the plants have aphid clustering under leaves, honeydew is present, and cotton is under drought stress.

 

ESCAPE BOLLWORMS   

For about 10-14 days, beginning July 20 in Central Alabama monitor squares and white blooms for small bollworm larvae.  Move this date 10 days earlier for South Alabama and 10 days later for North Alabama.  If the field has not been sprayed multiple times for plant bugs, fire ants will also be searching white blooms for these small larvae. Spray pyrethroid at a high labelled rate if 5 to 10 or more larvae about quarter inch in length are found per 100 plants.  You may look at fewer than 100 plants but express the number on a 100 percent basis. Tobacco budworms do not escape genetic cotton, therefore, even large bollworms can be controlled unless they are already imbedded in a boll.

STINK BUGS

Begin looking for stinkbug damage on field borders (first 5-10 rows) about the third week of bloom. This would be about July 20 in an average plant date year. Pull 10-25 bolls that are the size of a quarter in diameter and still soft to the touch. This boll would be about 10-12 days old. If you find internal damage on the border, search further into the field and collect more bolls.  Treat border and/or the entire field when 10% of these bolls have internal damage from stinkbugs. Damage will appear as warts in the boll wall or dark areas around the seed.  Continue scouting for stinkbugs until the top bolls you hope to harvest are about 25 days old and hard. Scout for 5-6 weeks beginning the third week of bloom.


SPIDER MITES      

Observe for the presence of spider mites underneath leaves. Mites will move when the leaf is pulled, inverted, and the mites are exposed to the sun. Treat when mites are detected over much of the field and the weather outlook for the next 7-10 days is hot and dry.  Mites do not reproduce or spread as fast when weather conditions are not favorable.  Rainfall does not kill mites, they just do not reproduce ad spread as rapidly.

 

Ronald SmithVisiting Professor (retd)Cooperative Extension Systems


Week of February 27, 2017

Tea scale crawlers are normally seen when wisteria blooms, but it appears that the very warm winter has allowed them to emerge over a long period of time already.  Various stages past the crawler stage, not yet armored, were seen on hollies.  Wisteria is just now starting to bloom.  Now would be a great time to control them with insecticide sprays directed to the undersides of the leaves. 

According to the National Phenology Network, spring is about 20 days early compared to yearly averages.   If you are interested, there is more to read about phenology, the art of reading nature. 

Southern red mites and half-grown lace bugs were seen on azaleas, mites were seen on compacta and Sky Pencil hollies, Blue Rug junipers, marigolds, and butterfly bush.  One juniper paria beetle was seen on Italian cypress.  This beetle feeds on the tips of various junipers.  Close inspection often reveals very small brown tips throughout the foliage.  Normally not noticeable, a few years ago Skyrocket juniper was so heavily fed on that it looked thin and spindly.  They can be found by shaking foliage over a white surface.

Mites from foliage

Neonicotinoid pesticide labels are now being printed with pollinator protection wording.  A bee hazard icon appears on these labels.  

Albert Van Hoogmoed

                AL Dept of Agriculture

                Mobile and Baldwin Counties

 



Sclerotinia White Mold was found on tomatoes growing in a greenhouse in east-central Alabama and in a strawberry production field in DeKalb County this week.  The report on tomato is not unusual as we have observed the disease on tomatoes and peppers in high tunnel operations in both 2015 and 2016.  However, the outbreak on strawberries is very unusual and has rarely been observed in the southeastern U.S.  I suspect the unusual winter weather has played a role in the development of the disease this year.

The fungal disease, which is also known as timber rot on tomato, has a wide host range of over 170 plant species. This disease affects a number of economically important vegetable crops.   Plants are most susceptible to infection during flowering, where a white cottony growth forms on all plant parts.  Young seedlings of tomato, pepper and other vegetables are also very vulnerable to the pathogen. 

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Sclerotinia white mold (timber rot) on greenhouse tomato.

The pathogen favors relatively cool temperatures from 60 to 70°F, especially nighttime temperatures of around 60°F.  The fungus can remain dormant in the soil for five years or more as hard, black sclerotia under an unfavorable (warn and dry) environment.    Under relatively cool and wet conditions, fruiting structures and spores are produced that can spread through the tunnel in water, wind, plant debris, and by workers.  The pathogen eventually forms a white cottony mycelium on flowers, stems, and leaves.  The fungus can also attack at the base of the stem causing infected plants to wilt and die. 

Management for high tunnels and greenhouse operations

  • Reduce excess moisture– If soils remain warm without continuous wet periods, the pathogen will be unable to germinate.  Keeping plant density low and pruning to increase air movement will aid in preventing excess moisture on the foliage.
  • Chemical Treatments – Preventative fungicide applications will help keep the disease from initially establishing.
  • Start with Clean Soil – Sclerotia overwinter in warm and dry soil. By sanitizing or sterilizing soil by soil fumigation, etc., the sclerotia will be destroyed.
  • Sanitation – Clean tools and machinery used in the high tunnels to prevent spread of the pathogen.  Remove fallen flower petals or dying plant material so that the pathogen cannot survive in the plant debris.  Carefully dig up diseased plants and remove soil in a 4-6 inch radius around the base of the stem to remove any sclerotia that may have fallen from the plant to the soil.

 

 Sclerotinia crown rot of strawberry typically attacks crowns directly at or near the soil line.  Invasion of petioles, flower trusses, and the terminal buds generally follows.  The fungus generally spreads to the crown after it colonizes dead leaves.  Abundant white, cottony mycelium is usually apparent on the diseased plants and numerous white to dark brown to black sclerotia form on this tissue.  The appearance of external white mycelium and the formation of black sclerotia are characteristic for this disease.

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Sclerotinia crown rot on strawberries.

 Avoiding infected fields is the best control.  There are no specific fungicides labeled to control Sclerotinia on strawberry, however fungicide with activity against Botrytis gray mold may suppress Sclerotinia croewn rot.  

Ed Sikora, Plant Pathologist, ACES

Kassie Conner, Plant Pathologist, ACES

Chip East, Regional Ext. Agent, ACES


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