Getting Powdery Mildew Under Control in Cucurbits, and Updates on Fungicides

for Vegetables

Mohammad BabadoostUniversity of Illinoisbabadoos@illinois.edu

Powdery Mildew of Cucurbits and Its

Management

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Cucurbits___________________________________ Melons Cucumbers Gourds Pumpkins (JOL & processing) Squash (summer & winter) Watermelon

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Cantaloupe Cucumber

Squash WatermelonPowdery mildew on cucurbits

Powdery Mildew: pumpkinBabadoost

Powdery Mildew: Pathogens_____________________________________ Two fungal species Podosphaera xanthii Erysiphe cichoracearum

Identification: difficult (sexual stage is not common)

We began identifying species

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Reproductive bodies of Podosphaera xanthii

Reproductive bodies of Erysiphe cichoracearum

Powdery Mildew: Symptoms_____________________________________ Symptoms & Sings Powdery fungal growth

(Mycelium and conidia) Infected tissues Vines Petioles Upper and lower leaf surfaces Fruit stems

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Powdery Mildew: vine infection

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Powdery Mildew: lower surface of leaf

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Powdery Mildew: upper surfaces of leaves

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Powdery Mildew: fruit stem

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Powdery Mildew: fruit stemsBabadoost

Powdery mildew fungus on plantsBabadoost

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Disease Cycle of Powdery Mildew

Cucurbits

Fungal Characteristics ____________________________________ Obligate parasite (biotrophic) Heterothalic (mating types) Sexual state: cleistothecium Asexual state: conidia Feed on epidermal cells Races have been documented

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Powdery Mildew Characteristics Occurrence: annually occurring Initial inoculum: conidia Inoculum sources: southern states and

greenhouses Conidia viability: 7-8 days Disease cycle: in 3-7 Favored: dryness with RH (50-100%) Temperatures: 50-90°F (68-80°F) Rain and water: unfavorable Yield losses: significant Babadoost

Susceptibility of Cucurbits to Powdery Mildew in the Midwest More susceptible cucurbits Squash (summer & winter) Pumpkins (JOL) Melons

Less susceptible cucurbits Cucumbers Processing pumpkinsWatermelons Babadoost

Expected Time for Powdery Mildew in Illinois and Indiana______________________________________ South: around July 15 Central and North: after July 20

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Important Management Point ______________________________________ Powdery mildew develops first

on vines Then, powdery mildew moves

onto lower leaf surfaces Powdery mildew on upper leaf

surfaces indicates outbreaks

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Powdery mildew on pumpkin Babadoost

Powdery mildew on cucurbits is the same

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Management of cucurbit Powdery Mildew _________________________________

Cultural management Plant resistance Biocontrol Chemical control

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Powdery Mildew Management ______________________________________

Cultural management Crop rotation Avoid shade areas Scout the field for powdery

mildew on vines and lower leaf surfaces

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Powdery Mildew Management ______________________________________

Plant resistance Resistant cultivars: many

resistant/tolerant cultivars of cantaloupe, cucumber, squash, pumpkin

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Crop Cultivar Crop CultivarCucumber Cyclone Pumpkin Big Moon

Thunder Jack-Be-LittleSlice King Magic Lantern

Melon Laguna MerlinAll Start MysticApolloOro DuroRocio

Squash HurakanSungloPatriot

Cucurbits Resistant/Tolerant to Powdery Mildew

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Management of cucurbit Powdery Mildew ______________________________________

Biocontrol AQ10 (Ampelomyces quisqualis),

fungus (Ecogen) Mycotal (Lecanicillium lecanii),

fungus (Koppert Biological Sys.) Serenade (Bacillus subtilis),

bacterium (AgraQuest) Babadoost

Powdery Mildew Management ______________________________________

Chemical control ˃ 15 Fungicides available

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Pumpkin & Squash:Cabrio (11)Flint (11)Fontelis (7)Inspire Super (3,9)Microthiol (S) (M)Merivon (7,11) Pristine (7,11)Procure (3)Quadris (11)Quadris Opti (11,M)Quintec (13)Rally (3)Topsin M (1)Torino (U6)

Cantaloupe, Cucumber, Watermelon:

Flint (11), Fontelis (7)Inspire Super (3,9)Luna Experience (3,7)Luna Sensation (7,11)Merivon (7,11)Microthiol (S) (M)Pristine (7,11)Procure (3), Quadris (11)Quadris Opti (11,M)Quintec (13)Rally (3), Satori (11)Topsin M (1), Torino (U6)

Fungicides for Cucurbit Powdery Mildew

Fungicides for Cucurbit Powdery MildewFRAC Fungicides Fungicide Group - Risk

1 Topsin M MBC (Methyl Benzimidazole Carbamates)

(Cell division) - High risk

3 Inspire Super, Procure, Rally, Luna Experience

DMI (Dethylation Inhibitors)(Cell membrane) - Medium risk

7 Fontelis, Merivon, Pristine, Luna Experience, Luna Sensation

SDHI (Succinate dehydrogenase inhibitors) (Respiration)- Medium-highrisk

9 Inspire Super AP (Anilino-pyrimidines) (Protein synthesis) - Medium risk

11 Cabrio, Flint, Merivon, Pristine, Quadris, Quadris Opti, Luna Sensation, Satori

Strobilurin: QoI (Quinone outside Inhibitors) (Respiration)- High risk

13 Quintec (Aza-naphthalenes) (Signal transduction) - Medium risk

M2 Microthiol (S) (Inorganic) (Multi-site activity) Low risk

U6 Torino (Phenyl-acetamide), Unknown

Fungicides for Cucurbit Powdery Mildew_______________________________________Most effective fungicides in my trials:

Quintec, Procure, Fontelis, Torino, Pristine, Quadris Opti, MicrothiolQuintec was the most effective Alternate Quintec with another fungicideStrobilurins are good for 10-14 days,

others for 7 days (max: 10 days)3-6 sprays are neededScout inside canopy, apply at first signPlan for spray during Jul 20 – Sep 10

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Updates on Vegetable Diseases______________________________________ 2015 Vegetable Production Guide Table 33 (pages 74-76): common and

scientific names of vegetable pests Table 12 (page 37): yields of vegetables

(updates)White rust: added to cole crops Bacterial fruit blotch: new recommendat. Merivon fungicide: cole crops, Brassica

leafy green, cucurbits, onion chapter Priaxor fungicide (7+11): fruiting vegetables Aoroach fungicide (11): legumes

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Updates on Vegetable Diseases______________________________________Cucurbit Disease Bacterial spot: a serious disease on

pumpkins, gourds, and winter squash. No effective control yet.

Sclerotinia blight of pumpkins: problem Edema: problem in white pumpkins Downey mildew: seed-borne reported Downy mildew control: chlorothalonil

prior to infection; Revus, Ranman, Zampro, Gavel … + chlorothalonil with disease sign infection

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Bacterial spot on squash fruit

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Collapse of pumpkin fruit infected by Xanthomonas cucurbitae

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Updates on Vegetable Diseases_____________________________________Cucurbit Disease Bacterial spot: a serious disease on

pumpkins, gourds, and winter squash. No effective control yet. Quintec fungicide has some effects

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BabadoostPumpkins with Sclerotinia sclerotiorum

BabadoostPumpkins with Sclerotinia sclerotiorum

Updates on Vegetable Diseases_____________________________________Cucurbit Disease Sclerotinia blight of pumpkins:

serious problem some years. Fontelis can be considered.

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Edema on white pumpkin in IL in 2014

Updates on Vegetable Diseases_____________________________________Cucurbit Disease Edema: problem in white pumpkins

(Moonshine)

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Downy mildew on cucumberBabadoost

Updates on Vegetable Diseases_____________________________________Cucurbit Disease Downey mildew: seed-borne reported Downy mildew control: chlorothalonil

prior to infection; Revus, Ranman, Zampro, Gavel … + chlorothalonil with disease sign infection

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Updates on Vegetable DiseasesOther Vegetable Disease Basil downy mildew: a serious disease,

effective control with either Quadris, Revus, or Ranman + ProPhyt

Tomato leaf mold (Vulvia fulva): now in indoor and outdoor production

Tomato white mold: now in more prevalent in high tunnel production

Tomato bacterial diseases: spot, speck, and canker. Bacterial spot is prevalent. Sprays of Quintec + Kocide-3000 alternated with mancozeb + Kocide-3000 suppress the disease.

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Downy mildew of basil on leaves

Updates on Vegetable DiseasesOther Vegetable Disease Basil downy mildew: a serious disease,

effective control with either Quadris, Revus, or Ranman + ProPhyt

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Leaf mold of tomato in a high tunnel Babadoost

Updates on Vegetable DiseasesOther Vegetable Disease Tomato leaf mold (Vulvia fulva):

now in indoor and outdoor production

Fungicides:ChlorothalonilMancozebInspire SuperQuadris TopTanos

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White Molds (Sclerotinia sclerotiorum)Babadoost

White Molds (Sclerotinia sclerotiorum)Babadoost

Updates on Vegetable DiseasesOther Vegetable Disease Tomato white mold: now in more

prevalent in high tunnel production.

Fungicides: Cabrio (11)Cantans (biological fungicide,Coniothyrium minitans strain CON/M/91-08) Priaxor (11)

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Bacterial SpeckBacterial SpotBacterial Canker

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Bacterial spot

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Updates on Vegetable DiseasesOther Vegetable Disease Tomato bacterial diseases: spot, speck,

and canker. Bacterial spot is prevalent. Sprays of Quintec + Kocide-3000 alternated with mancozeb + Kocide-3000 suppress the disease.

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