Mississippi Fruit Problems 2015

Every year the Mississippi State University Extension Plant Diagnostic Lab published a list of the pathogens/problems that were identified.  The Lab can be found online here: msucares.com/lab.  In 2015 several pathogens/problems were seen on fruit crop plants in Mississippi.  Below is the run-down. The number after the name indicates how many times it was diagnosed in 2015:

Apple (Malus x domestica)
 Abiotic (Potassium deficiency suspected) (1)
 Alternaria blotch (Alternaria mali) (1)
 Bitter rot (Colletotrichum sp.) (1)
 Burrknot (genetic) (1)
 Cedar apple rust (Gymnosporangium juniperi-virgianae) (1)
 Cedar apple rust resistance reaction (Gymnosporangium juniperi-virgianae) (2)
 Flyspeck (Schizothyrium pomi) (1)
 Leaf spot (Gloeosporium sp.) (1)
 Leaf spot (Pseudocercospora sp.) (1)

Banana, Japanese (Musa basjoo)
 Root rot (Pythium sp.) (1)

Blackberry (Rubus sp.) ‘Arapaho’
 Abiotic (herbicide injury) (1)

Blueberry (Vaccinium sp.)
 Canker (Fusicoccum sp.) (1)
 Leaf and Fruit Spot (Exobasidium maculosum) (1)

Cherry (Prunus sp.)
 Leaf spot (Cercospora circumscissa) (1)
 Shot-hole (Wilsonomyces carpophilus) (1)

Chestnut, Chinese (Castanea mollisima)
 Abiotic (high pH) (1)

Fig, Common (Ficus carica)
 Fig canker suspected (Diaporthe eres) (1)
 Web blight (Rhizoctonia solani) (1)
 Wood boring beetles (1)

Lemon (Citrus limon)
 Alternaria leaf spot of rough lemon suspected (Alternaria sp.) (1)

Mayhaw (Crataegus aestivalis)
 Rust (Gymnosporangium sp.) (1)

Muscadine (Vitus rotundifolia)
 Leaf blight (Pseudocercospora vitis) (1)

Peach (Prunus persica)
 Bacterial spot (Xanthomonas arboricola pv. Pruni) (1)
 Brown rot (Monilinia fructicola) (4)
 Shot-hole (Wilsonomyces carpophilus) (1)

Pear (Pyrus sp.)
 Bacterial shot-hole disease (Pseudomonas syringae) (1)
 Cedar quince rust (Gymnosporangium clavipes) (2)
 Leaf spot (Phoma sp.) (1)
 Spot anthracnose (Elsinoë pyri) (2)

Pecan (Carya illinoinensis)
 Aphid injury suspected (1)
 Burl (undetermined cause) (1)

Plum (Prunus sp.)
 Black-knot (Apiosporina morbosa) 91)
 Gummosis (Botryosphaeria sp.) (1)
 Shot-hole disease (Wilsonomyces carpophilus) (1)
 Shot-hole borer suspected (1)

Satsuma (Citrus reticulata)
 Abiotic (nutrient deficiency suspected) (1)
 Abiotic (alternate bearing) (1)
 Fruit drop (abiotic) (1)
 Fruit split (abiotic) (1)
 Sweet orange scab suspected (Elsinoe fawcettii) (1)

Strawberry (Fragaria sp.)
 Abiotic (acetochlor plus heavy clay soil plus cold wet weather suspected) (1)
 Abiotic (nutrient deficiency suspected) (1)
 Abiotic (root stress-too wet) (1)
 Bacterial leaf scorch (Xylella fastidiosa) (1)

 

Is Mummy Berry Starting Already?

I received the information below from University of Georgia Plant Pathologist Dr. Phil Brannen. It states that in Georgia, mummy berry infection is likely right now due to the warmer weather conditions.  We have also had these conditions in Mississippi, so it would be a good idea to keep mummy berry control in mind, especially for southern highbush blueberries.  Meanwhile, rabbiteyes are not far behind.

Dr. Harald Scherm ran the mummy berry model today, and it indicates that we are currently in a DANGER period for mummy berry disease initiation.  Harald stated that the temperature-driven model indicated that apothecium (spore-forming structure that develops from overwintered mummies on the ground and in debris) emergence should be well underway based on the balance of chill-hours and degree-days received. In fact, there could be a chance that the apothecia ejected spores earlier than normal, possibly allowing for infection of early-blooming southern highbush varieties. This assumes that soil moisture conditions have been favorable, which they likely have been.  Rabbiteyes will soon be showing green tip or early bloom, which should initiate the spray program for mummy berry management.  For additional information on fungicides which are available for management of mummy berry, refer to the blueberry IPM guide at www.smallfruits.org. “

Curious Galls on Muscadine Vine

Recently, a muscadine vine cane was brought into the lab after pruning. It had galls along the cane at nearly every node. Grape cane gallmaker (http://nysipm.cornell.edu/factsheets/grapes/pests/gcgm/gcgm.pdf) may be the culprit, but there are other types of gall making insects around as well that could cause similar injury.  We were not able to find any evidence of larvae, frass, or any other trace of the insect. The injury to the cane is quite extensive, but luckily only a very few canes were harmed.  Thus, it is not worth trying to control this insect, as it would not create economic-scale damage to the vine or to yields. See the photos below.

Galls on cane of a muscadine vine

Galls on cane of a muscadine vine

Closer image of the galls. No evidence of the pest was found (aside from the swelling).

Closer image of the galls. No evidence of the pest was found (aside from the swelling).

Crow Away!

I want to start off upfront with a few things: First, I am not an expert on crow behavior, Second I am a fan of The Black Crowes, Counting Crows, and A Murder of Crows, and Third, I know crows can be a nuisance.

I’m not sure what programs exist in Mississippi to control these bird pests.  I know the Department of Wildlife Conservation in Oklahoma had a program for control, but I am not sure if Mississippi has anything similar. In Oklahoma crows are a significant pest of pecans.

I found a couple links with information on controlling them in Mississippi and it looks like they can be killed if needed to protect crops.

http://icwdm.org/handbook/birds/AmericanCrows.asp

“Crows are protected by the Migratory Bird Treaty Act, a federal act resulting from a formal treaty signed by the United States, Canada, and Mexico. However, under this act, crows may be controlled without a federal permit when found “committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner to constitute a health hazard or other nuisance.”

States may require permits to control crows and may regulate the method of take. Federal guidelines permit states to establish hunting seasons for crows. During these seasons, crows may be hunted according to the regulations established in each state. Regulations or interpretation of depredation rules may vary among states, and state or local laws may prohibit certain control techniques such as shooting or trapping. Check with local wildlife officials if there is any doubt regarding legality of control methods.”

https://www.animallaw.info/statute/ms-hunting-%C2%A7-49-1-39-killing-animals-or-birds-injurious-agriculture-exception-migratory

“Statute Text

  • 49-1-39. Killing animals or birds injurious to agriculture; exception as to migratory birds

The commission may issue permits to kill any species of animals or native, nonmigratory birds which may become injurious to agricultural or other interests in any particular community. All migratory birds, including hawks, owls, and eagles and their nests and eggs are protected by the Migratory Bird Treaty Act and federal regulations promulgated under this act. All species of blackbirds, cowbirds, starlings, crows, grackles, and English sparrows may be killed without a permit when such birds are committing or about to commit depredations on shade or ornamental trees or agricultural crops.”

Now, eliminating (killing) crows is not always necessary.  Often exclusion is the best option if possible.  Scare tactics or repellents can also work, but usually only for a limited time period as the crows become wise to it.

My suggestion, if elimination is necessary, would be to contact the US Fish and Wildlife folks in Jackson for more info: http://www.fws.gov/jacksonwildlife/.  Also available is The Center for Resolving Human-Wildlife Conflicts at Mississippi State University which can be found at this website: http://www.humanwildlifeconflicts.msstate.edu/#&panel1-1

Netting Grapevines Against Birds

Last year I had problems with birds destroying some grapes before I had the chance to harvest them (full disclosure: I had several conferences last year that I attended while it was close to harvest time.  I rolled the dice that the fruit would still be there when I got back — no such luck). This year I am taking no chances!  Last week the bird netting went up on two of the four rows in the vineyard and this week the other two will be covered as well.  Since the vineyard is so small, it was relatively easy to put the netting over the rows and secure it.  Below are a few photos (taken by Richelle Stafne) of the process.

Throwing the netting over the row.  It helps to be tall.

Throwing the netting over the row. It helps to be tall.

Pulling the netting over the vines to make sure it covers the canopy.

Pulling the netting over the vines to make sure it covers the canopy.

Securing the netting by using zip ties. Other materials can be used such as string, twine, or bread ties. The netting was tied to the irrigation wire with the zip ties.

Securing the netting by using zip ties. Other materials can be used such as string, twine, or bread ties. The netting was tied to the irrigation wire with the zip ties.

The job is finished and we admire our efforts while sweating in 90+F heat and humidity.

The job is finished and we admire our efforts while sweating in 90+F heat and humidity.

The netting will remain on until harvest.  Once all fruit is harvested it will be removed and stored for next year.  Netting is an added expense to the vineyard and it makes management more difficult, but it is a necessity to protect the fruit from birds. There are different kinds of netting, some will last longer than others (and hence are more expensive), so it depends on an individual managers needs which kind to purchase.  Tractor implements are available to help with this process in large-scale operations.

Anthracnose on Bunch Grapes

More rain is falling today and is expected for the next few days.  All this wet and cooler weather creates good conditions for anthracnose infections.  Anthracnose (Elsinoe ampelina) can be severe in years with heavy and consistent rainfall (like this year).  Optimal conditions for disease development are in the upper 70s F.  The spores are splashed from plant to plant by rain.  It is seen most commonly on young, succulent green shoots and leaves.  The lesions are sunken on shoots and on leaves the leaves can be distorted and have a shot-hole appearance.  A photo of the disease on a ‘Victoria Red’ cluster is below.

Severe anthracnose infection on Victoria Red grape cluster

Severe anthracnose infection on Victoria Red grape cluster

How can anthracnose be controlled?  If you are in the Deep South, not too easily, I’m afraid.  Sanitation can help (get rid of infected plant parts).  Canopy management that promotes sunlight penetration and good airflow can also help.  But likely the best way is a dormant fungicide spray or two of lime sulfur followed by subsequent fungicide applications until veraison. More in-depth information can be found here:

http://www.smallfruits.org/smallfruitsregguide/Guides/2015/BunchGrapeSprayGuide2015.pdf

Popcorn Disease of Mulberry

Popcorn disease of mulberry is caused by a fungus (Ciboria carunculoides).  It occurs in late spring and early summer.  The white mulberries are more susceptible to this disease.  The disease manifests on the developing carpels and looks like popcorn kernels.  It is a serious disease if the tree is being cropped for commercial purposes; however, it does no harm to the overall health of the trees, thus homeowners do not need to worry (if the tree is only used for ornamental or shade purposes). So, if this disease does occur what can be done to stop it?  Sanitation is a good first step — clean up any infected material and remove it from the area where the tree is growing.  There is very little else a homeowner can feasibly do to reduce the disease.  Spraying the tree with Bordeaux mixture may help too, but getting coverage over the entire tree may be problematic. As with many fungal diseases, the severity will depend on the environmental conditions from year to year.  Some years will be worse than others.

Popcorn Disease of Mulberry

Popcorn Disease of Mulberry

If you wish to read more on this particular disease, Texas A&M has a good, short fact sheet on it here.

Be Careful Using Herbicides

Glyphosate (i.e. RoundUp) has been getting a lot of bad press lately, mainly as it relates to GMOs.  This post is not about GMOs, but rather prudent use of herbicides. Herbicides are great tools, but must be used with caution. First of all, the label is the law, so any instruction supplied on the side of the herbicide container is what one must follow for application (an online version of the label IS NOT considered to equivalent to the actual one on the container).  Second, make sure the tanks you use are either dedicated for the type of pesticide being applied (one for herbicides, one for insecticides and/or fungicides, etc.).  Third, clean out the tank, especially if you are changing products.  Residue can lead to unintended consequences.  Fourth, understand the mode of action and rotate chemistries to reduce the chance for weed resistance. Fifth, know which weeds you want to control and use the best product for those weeds.  Sixth, timing of application is VERY important for control — knowing the weed life cycle and timing the herbicide application with the most vulnerable period will yield the best results. There are some rules to follow when using any herbicide, but since glyphosate is so ubiquitous some closer scrutiny is needed.

Now, on to glyphosate specifically.  It is a systemic herbicide, meaning the product is taken up by the plant and translocated within it.  Glyphosate inhibits plant enzyme production, thus disruption its ability to synthesize certain amino acids.  So, it is very good at killing a broad spectrum of weed species.  Unfortunately, if not applied properly, it can be very good at killing fruit and nut plants too.  Since RoundUp went off patent, there are many glyphosate products on the market now.  Some have very different percent active ingredient.  Knowing the percent active ingredient will tell one how much water to mix it with prior to application.  Still, sometimes errors are made and a high price is paid.

A recent visit I had to a blueberry field revealed significant damage from glyphosate application.  The grower had good intentions and had used glyphosate without problem for years, he had run out of one container and switched to another new one.  Several rows had no problems (application with the first container), but the next rows had significant death.  Why? The amount of active ingredient was different, but the applicator mixed the same amount for application.  The plants may never recover and probably need to be removed.  The photo below tells the story.  If in any doubt about applying herbicides properly, contact a local county Extension office for help.

Herbicide damage to blueberry plant

Glyphosate herbicide damage to blueberry plant

Flea Beetle Damage in the Vineyard

Flea beetles are an early season pest in the vineyard.  Both the adults and larvae are present during the Spring.  The best time to control this pest is at bud swell, as if not controlled they will continue to cause problems later as larvae.  Several products can be used to control flea beetles in the vineyard, such as Sevin, Danitol, Baythroid, etc.  See the photo below for the kind of damage the larvae can inflict on leaves (but also blooms).  Adult beetles will feed on swelling primary buds, and this is the more serious type of damage that occurs.  If this is a problem, they should be controlled to prevent a reduction in shoots (and crop) in the following years.

Flea beetle larvae feeding damage

Flea beetle larvae feeding damage

Ambrosia Beetles Found in Muscadine Vines

Now muscadine growers have a new pest to concern themselves with in south Mississippi.  Recently, Chris Werle (USDA-ARS Thad Cochran Southern Horticultural Laboratory Poplarville, MS) found ambrosia beetles attacking muscadine vines.  These beetles are extremely harmful to the plants they attack.  Not only do the beetles attack the plant, but they also transmit a fungus (e.g. Fusarium spp.) that can eventually take down the plant.  Infested plant parts should be removed and destroyed.  Plants showing heavy infestation and/or significant related disease symptoms should be removed to halt further spread.  Control must be done before the beetle burrows into the plant.  The two links below have suggestions as well as photos of the pest.

North Carolina State University http://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note111/note111.html

Clemson University http://www.clemson.edu/cafls/departments/esps/factsheets/turforn/ambrosia_beetles_to22.html

Below are some photos from Chris Werle of ambrosia beetle damage on muscadine and fig.

Ambrosia beetle damage on fig. Notice sawdust from boring hole

Ambrosia beetle damage on fig. Notice sawdust from boring hole (Photo by Chris Werle)

A trunk of a muscadine vine heavily infested by ambrosia beetle. Notice the many entry holes. (Photo by Chris Werle)

A trunk of a muscadine vine heavily infested by ambrosia beetle. Notice the many entry holes. (Photo by Chris Werle)

Ambrosia beetle damage on muscadine vine cordons.  Diagnostic "straws" of sawdust indicate the presence of the insect. (Photo by Chris Werle)

Ambrosia beetle damage on muscadine vine cordons. Diagnostic “straws” of sawdust indicate the presence of the insect. (Photo by Chris Werle)