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)



Agenda for 2015 Muscadine Field Day

Below is the agenda for the 2015 Muscadine Field Day.  It will be held tomorrow morning.  More detailed information, including location, times, etc. was published on this blog here: https://msfruitextension.wordpress.com/2015/07/14/mississippi-muscadine-field-day-2015/

2015 Muscadine Field Day Agenda

2015 Muscadine Field Day Agenda

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)

Online Muscadine Resources Presentation

This past weekend I gave a presentation at the SE Regional Fruit and Vegetable Conference in Savannah, GA.  The topic was “Online Muscadine Resources: Present and Future”.  It was in the Muscadine section and we had some great talks and lots of good discussion there.  Below you can download a pdf of my presentation as well as a handout with links to some online muscadine resources.

Online Muscadine Resources: Present and Future

Muscadine Online Resources, Savannah 2014

Fungicide applications affect fruit diseases and quality of muscadine grape

Another teaser for the 2013 Muscadine Field Day — see the abstract below provided by Dr. Barbara Smith, USDA-ARS Plant Pathologist.

Fungicides can significantly reduce losses due to disease in the yield and quality of muscadine grapes. In four studies fungicides were applied individually or as part of a full season schedule from early bloom until harvest to three muscadine grape cultivars. The objective was to compare the effect of a full season treatment of 9-12 fungicide applications applied on a 10-day interval to fewer applications of individual fungicides on disease incidence, yield, and berry quality. Foliar and berry diseases were rated on visual scales. Sugars, acids, ellagic acid, and resveratrol content were determined by HPLC.

Four studies explored the relationship between disease control, berry quality, and phytochemical content following full season or early season application fungicides.  In each study foliar and fruit diseases were lower in the full season treatment compared to the control, each fungicide was effective in reducing at least one disease, and some treatments with fewer applications reduced fruit diseases to the same level as the full season treatment.  In Study 1, the full season treatment of 9 applications applied at 10-days intervals and the azoxystrobin treatment of 3 applications applied at 30-day intervals resulted in significantly higher yields, lower fruit disease scores, and more asymptomatic berries than the control treatment.  In Study 2, four applications of the azoxystrobin, myclobutanil, and the combination fungicide, cyprodinil plus fludioxonil applied at 30-day intervals were as effective in reducing total berry diseases as the full season schedule of 12 applications (three fungicides alternated at 10-day intervals).  In Study 3, three fungicides were applied on an alternating schedule every 10 days beginning at bloom and stopping at various pre-harvest intervals.  There were no significant differences in vine vigor, foliar diseases scores, percentage of asymptomatic berries, or bitter rot scores due pre-harvest interval.  In Study 4, there was not a significant difference in the percentage of asymptomatic berries between the full season treatment of eight applications and early season treatment of four applications or in the bitter rot and total disease scores for five of the fungicide treatments.  Data indicate that fungicide applications can be stopped as early as six weeks before harvest without significant effects on berry diseases.

Studies 1 and 3 also investigated the effect of fungicide treatments on berry quality and phytochemcial content.  In Study 1, significant differences were found in pH, TA, fructose, glucose, tartaric acid, and resveratrol levels.  Total resveratrol was lower in the skins of berries from the full season and azoxystrobin treatments than from the control and other fungicide treatments.  Berries from the least efficacious treatments for berry diseases had almost ten times as much resveratrol as those from the full season and azoxystrobin treatments.  In Study 3, ellagic acid content was lower in berries from the spray treatment than from the not sprayed and control treatments.  Total resveratrol content was approximately four times higher in skins of berries that did not receive fungicide sprays than in those that did.  Resveratrol levels in the skins of berries from fungicide treatments were very low even if the last fungicide application was 8 weeks before harvest.

Data from these four studies indicate that the number of fungicide applications required for control of muscadine grape diseases can be reduced without an increase in berry rot disease severity.  The most effective fungicides reduced berry diseases with as few as four applications compared to 12 applications in the full season schedules.  Fungicides that controlled berry disease had an effect on berry quality including lowering the content of the beneficial phytoalexin, resveratrol.