Taking an environmentally sensitive approach to pest management


Missouri Environment & Garden



AUTHOR

Patricia K. Hosack
University of Missouri
Division of Plant Sciences
(573) 882-3019
hosackp@missouri.edu

Plant Diagnostic Clinic: End of the Year Summary for Horticultural Plants

Patricia K. Hosack
University of Missouri
(573) 882-3019
hosackp@missouri.edu

Published: December 14, 2015

As of December 11th, 2015, the Plant Diagnostic Clinic (PDC) had 403 samples submitted.  Most of the the samples were submitted for disease diagnosis, though some were for insect or plant identification (Figure 1). Despite the excessive rain and cool summer temperatures, growers and homeowners still had plant health issues to deal with. The diversity of horticultural plants submitted to the clinic was vast. A complete list of diagnosed diseases, by host, can be found below (Tables 1-4).  Abiotic issues, such as chemical injuries or environmental issues, were also diagnosed in all the sample categories (Figure 2).  

Due to the a rain-filled spring and early summer, not surprisingly, diagnosis of Pythium and Phytophthora diseases were numerous in many hosts. Both pathogens are oomycetes, or water molds, meaning they love water and cause epidemics quickly in saturated situations.  Both organisms take advantage of excess water by producing a motile spore called a zoospore, that uses flagella to swim from root to root or plant to plant. Bacterial diseases were also commonly diagnosed in a multitude of hosts, since rain splash moves these organisms from leaf to leaf. Numerous fungal diseases were also diagnosed on evergreen ornamentals. We saw a reduction of these with the warmer, drier weather of late July - September, but observed a resurgence in late October and November.

The PDC is open year round for sample submission. The typical turn around is 48 hours, depending on the day of the week the sample is submitted. If special testing is required, such as an ELISA or culture plating, turn around time varies. A general diagnosis is $15, additional services are $10 each.  For horticultural crops, additional services may include culture plating, serological assays (ELISA or immunotrips) or other miscellaneous molecular testing methods. 

Please see the PDC website (http://plantclinic.missouri.edu) or call (573-882-3019) for more information.

Figure 1:


Figure 2:
             

Table 1:  Diagnosed Pest Issues on Vegetables


Host

Diagnosis (Causal agent): Number of confirmed samples

Bell Pepper

Alternaria Leaf Spot (Alternaria spp.) : 1

Bell Pepper

Bacterial Leaf Spot (Xanthomonas spp.) : 1

Broccoli

Black Spot (Alternaria spp.) : 1

Cabbage

Black Spot (Alternaria spp.) : 1

Cucumber

Anthracnose (Colletotrichum orbiculare) : 1

Cucumber

Bacterial Soft Rot (Unidentified Bacterium) : 1

Garlic

Bacterial Soft Rot (Erwinia spp.) : 1

Kale

Black Spot (Alternaria spp.) : 1

Napa; Chinese cabbage

Black Spot (Alternaria spp.) : 1

Pumpkin

Fusarium Crown Rot (Fusarium solani f.sp. cucurbitae) : 1

Rhubarb

Slugs (Mollusca; Gastropoda) : 1

Tomato

Alternaria Leaf Spot (Alternaria spp.) :  1

Tomato

Bacterial Canker (Clavibacter michiganensis michiganensis) : 1

Tomato

Brown root rot (Colletotrichum coccodes) : 1

Tomato

Early Blight (Alternaria solani) : 5

Tomato

Fusarium Crown Rot (Fusarium spp.) : 1

Tomato

Gray Mold (Botrytis cinerea) : 1

Tomato

Lesion Nematodes (Pratylenchus spp.) : 1
* Confirmed by Nematology Lab (http://soilplantlab.missouri.edu/nematode/)

Tomato

Onion Thrips (Thrips tabaci) : 1

Tomato

Root-knot Nematodes (Meloidogyne spp.) : 2
* Confirmed by Nematology Lab (http://soilplantlab.missouri.edu/nematode/)

Tomato

Septoria Leaf Spot (Septoria spp.) : 2

Tomato

Southern Blight (Sclerotium rolfsii) : 1

Zucchini Squash

Cucurbit Bacterial Wilt (Erwinia tracheiphila) : 1

Table 2: Diagnosed Pest Issues on Fruits


Host

Diagnosis: (Causal agent): Number of confirmed samples

Apple

Fire Blight (Erwinia amylovora) : 1

Blackberry

Spur; Cane Blight (Didymella applanata) : 1

Blueberry

Alternaria Leaf Spot (Alternaria spp.)  : 1

Blueberry

Crown and Root Rot (Phytophthora spp.) : 1

Blueberry

Gloeosporium Leaf Spot (Gloeosporium spp.) :1

Cantaloupe

Alternaria Leaf Blight (Alternaria spp.) : 1

Cantaloupe

Alternaria Leaf Blight and Spot (Alternaria cucumerina) : 1

Cantaloupe

Cucurbit Bacterial Wilt (Erwinia tracheiphila) : 1

Grape

Bitter Rot (Greeneria uvicola) : 1

Grape

Crown Gall (Agrobacterium vitis) : 1

Grape

Grape Downy Mildew (Plasmopara viticola) : 2

Grape

Grape Phylloxera (Daktulosphaira vitifoliae) : 1

Grape

Pierce's Disease (Xylella fastidiosa) : 1

Grape

Leaf Spot (Pestalotia spp.) : 2

Grape

Phomopsis Rachis Rot (Phomopsis spp.) : 1

Peach

San Jose Scale (Diaspidiotus perniciosus) : 1

Peach

Scab (Cladosporium spp.) : 1

Pear

Fire Blight (Erwinia amylovora) : 1

Pear

Pear Stony Pit (Pear Stony Pit Virus) : 1

Strawberry

Cylindrocarpon Crown Rot (Neonectria spp.) : 1

Strawberry

Powdery Mildew (Podosphaera macularis) : 1

Strawberry

Twospotted Spider Mite (Tetranychus urticae) : 2

Watermelon

Alternaria Leaf Blight or spot (Alternaria spp.) : 4

Watermelon

Anthracnose (Colletotrichum orbiculare) : 1

Watermelon

Aphids (Aphis spp.) : 1

Watermelon

Bacterial Fruit Blotch (Acidovorax avenae citrulli) : 1

Watermelon

Cercospora Leaf Spot (Cercospora spp.) : 2

Watermelon

Cucurbit Gummy Stem Blight (Didymella bryoniae) : 1

Watermelon

Fusarium Fruit Rot (Fusarium spp.) : 1

Watermelon

Phytophthora Fruit Rot (Phytophthora spp.) : 2

Table 3: Diagnosed Pest Issues on Ornamental plants.       


Host

Diagnosis: (Causal agent): Number of confirmed samples

Arborvitae

Kabatina Twig Blight (Kabatina thujae) : 1

Ash

Ash Decline Complex (Unidentified Agent) : 1

Ash

Ash Flower Gall Mite (Eriophyes fraxiniflora) : 2

Ash

Mycosphaerella Leaf Spot (Mycosphaerella spp.) : 1

Boxwood

Armored Scales (Family Diaspididae) : 1

Boxwood

Macrophoma Leaf Spot (Macrophoma candollei) : 1

Boxwood

Volutella Leaf Blight (Volutella spp. ) : 1

Burning Bush

Mealybug (Family Pseudococcidae.) : 1

Eastern Red cedar

Needle Blight (Cercospora spp.) : 1

Chinese Chestnut

Wood Decay Fungus (Unidentified Fungus) : 1

Chrysanthemum

Alternaria Leaf Blight (Alternaria spp.) : 1

Chrysanthemum

Pythium Root and Crown Rot (Pythium spp.) : 1

Flowering Dogwood

Dogwood Anthracnose (Discula destructiva) : 1

American Elm

Dutch Elm Disease (Ophiostoma spp.) : 1

Elm

alcohol flux : 1

Douglas-fir

Diplodia Tip Blight (Diplodia pinea) : 1

Douglas-fir

Phomopsis Tip Blight (Phomopsis juniperovora) : 1

Geranium

Gray Mold (Botrytis cinerea) : 1

Holly

Alternaria Leaf Spot (Alternaria spp.) : 1

Holly

Armored Scales (Family Diaspididae) : 2

Holly

Canker and Dieback (Botryosphaeria dothidea)  2

English Ivy

Anthracnose (Colletotrichum spp.) : 1

Juniper

Seiridium Canker (Seiridium spp.) : 3

Juniper

Eastern Juniper Bark Beetle (Phloeosinus dentatus) : 1

Juniper

Juniper Scale (Carulaspis juniperi) : 1

Juniper

Phomopsis Tip Blight (Phomopsis juniperovora) : 1

Leyland Cypress

Seiridium Canker (Seiridium spp.) : 1

Japanese Maple

Dieback; Canker; Twig Blight (Botryosphaeria spp.) : 1

Japanese Maple

Bark Beetles (Family Scolytidae) : 1

Maple

Anthracnose (Colletotrichum spp.) : 2

Maple

Armillaria Root Rot (Armillaria spp.) : 1

Maple

Armored Scales (Family Diaspididae) : 1

Maple

Spider Mites (Family Tetranychidae) : 1

Maple

Termites (Order isoptera) : 1

Million Bells

Pythium Root and Crown Rot (Pythium spp.) : 1

Oak

Armored Scales (Family Diaspididae) : 1

Oak

Bacterial Leaf Scorch (Xylella fastidiosa) : 6

Oak

Bark Beetles (Family Scolytidae) : 3

Oak

Canker (Hypoxylon spp.) : 1

Oak

Dieback; Canker; Twig Blight (Botryosphaeria spp.) : 1

Oak

Horned Oak Gall Wasp (Callirhytis cornigera) : 2

Oak

Foliar Insect Gall (Insect Gall) : 2

Oak

Tubakia Leaf Spot (Tubakia dryina) : 2

Oak

Powdery Mildew (Erysiphe alphitoides) : 1

Oak

Oak Wilt (Ceratocystis fagacearum) : 3

Oak

Spider Mites (Family Tetranychidae) : 2

Phlox

Anthracnose (Colletotrichum spp.) : 1

Pine

Brown Spot Needle Blight (Mycosphaerella dearnessii) : 2

Pine

Pine Needle Scale (Chionaspis pinifoliae) : 1

Pine

Bark Beetles (Family Scolytidae) : 1

Privet

Armillaria Root Rot (Armillaria spp.) : 1

Rose

Alternaria Leaf Spot (Alternaria spp.) : 1

Rose

Anthracnose (Colletotrichum spp.) : 1

Rose

Powdery Mildew (Unidentified Fungus) : 1

Norway Spruce

Spruce Spider Mite (Oligonychus ununguis) : 1

Norway Spruce

Sudden Needle Drop (Setomelanomma holmii) : 2

Spruce

Pine Needle Scale (Chionaspis pinifoliae) : 1

Spruce

Rhizosphaera Needle Cast (Rhizosphaera kalkhoffii) : 2

Spruce

Cytospora Canker; Dieback (Cytospora spp.) : 1

Spruce

Phomopsis Tip Blight (Phomopsis juniperovora) : 1

Spruce

Soft Scales (Family Coccidae) : 1

Dwarf Alberta spruce

Adelgid (Adelges spp.) : 1

Supertunia

Alternaria Leaf Blight (Alternaria spp.) : 1

Sweetgum

Bacterial Leaf Scorch (Xylella fastidiosa) : 1

Viburnum

Bacterial Blight (Pseudomonas syringae syringae) : 1

Weeping Cherry

Dieback; Canker; Twig Blight (Botryosphaeria spp.) : 1

Weeping Cherry

Fire Blight (Erwinia amylovora) : 1

Witch Hazel

Phyllosticta Leaf Spot (Phyllosticta hamamelidis) : 1

Yew

Mealybugs (Family Pseudococcidae) : 1

           
Table 4: Diagnosed Pest Issues on Turfgrass. 


Host

Diagnosis: (Causal agent): Number of confirmed samples

Bluegrass

Brown Patch (Rhizoctonia solani.) : 1

Bluegrass

Summer Patch (Magnaporthiopsis poae) : 2

Bluegrass

Grub damage (Various scarab beetle larva): 2

Tall Fescue

Seedling Damping Off (Pythium spp.) : 1

Tall Fescue

Brown Patch (Rhizoctonia solani.) : 1

Mixed turfgrass

Slime Mold (Class Myxogastria) : 1

Mixed turfgrass

Gray Leaf Spot (Pyricularia grisea) : 1

 

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REVISED: December 14, 2015