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)

 

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)

Gettin’ Figgy With It

The LSU AgCenter has recently released 3 varieties of figs.  ‘O’Rourke’, ‘Champagne’, and ‘Tiger’ are new additions to the LSU fig program that includes ‘LSU Purple’ and ‘LSU Gold’.  Dr. Allen Owings of the LSU Hammond Research Station was kind enough to send a description of all the new varieties.  It can be downloaded at the link below:

New LSU AgCenter Figs

The plants may be a little difficult to find initially.  Almost Eden plant nursery has some of them listed, but are currently out of stock.    However, some searching around on the internet and interacting with fig growers in Louisiana may yield some good results.  Figs in Mississippi are grown widely, but not on a commercial scale.  These new varieties should be good for backyard growers.

Figs are popular with homeowners in Mississippi and new varieties could expand options

Figs are popular with homeowners in Mississippi and new varieties could expand options

Why do Figs Drop Leaves?

Figs can drop leaves for several reasons, including drought, poor nutrition, and disease.  The latter is what I will discuss today.  The most prominent defoliating disease of figs in our region is fig rust.  Unfortunately for those of us in Mississippi,  I cannot find any labeled fungicides for control of fig rust.  If you are in another state, check with you local county extension office for other options.  Some publications recommend a “neutral (fixed) copper spray”, but I can’t find a product in the database that fits that description.  The option is to make your own, called Bordeaux Mixture.  These links will tell you how to make it:

http://msucares.com/newsletters/pests/infobytes/19990915.htm

http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7481.html

Application should start just before budbreak in late winter.  Application in hot temperatures (>80F) will likely cause damage to the plant.  If rainfall and humidity is high then multiple application may be necessary about 1 week apart.  Fixed copper fungicide sprays (e.g. tribasic copper sulfate, copper oxychloride sulfate, and cupric hydroxide) may also work for this and is somewhat less toxic to the plant once it starts to grow in the spring.  This disease may be difficult to control fully in our environment when it is rainy and humid.  The leaves will eventually fall off the tree and be replaced by new ones (see photo below).  Sanitation (picked up and discarding infected leaves) is important for future control too.I suggest starting a spray regimen that continues through the spring.  Since the fungus only infects leaves it is not a problem on fruit.  However, lack of leaves can cause a reduction in following years fruit production and also a reduction in cold hardiness.Pruning trees to allow more sunlight penetration into the canopy and making sure the trees are spaced far enough apart may also help.

New leaves emerging on a young fig plant after prior defoliation

New leaves emerging on a young fig plant after prior defoliation (photo courtesy of Dr. Rick Snyder, MSU)