Updates on Powdery Mildew and other Diseases of Cucurbits Powdery Mildew and Its Management Mohammad University of Illinois babadoos@illinois.edu 5 January 2017 Powdery Mildew on Cucurbits Serious disease on: Pumpkins (JOL & processing) Squash (summer & winter) Melons Powdery Mildew: Symptoms Symptoms & Sings Powdery fungal growth (Mycelium and conidia) Infected tissues Vines Petioles Upper and lower leaf surfaces Fruit stems Powdery Mildew: vine infection Powdery Mildew: lower surface of leaf 1
Powdery Mildew: upper surfaces of leaves Powdery Mildew: fruit stems Our Powdery Mildew Project Identify pathogen species Determine genetic variation Disease Management Italy Chile Locations of powdery mildew samples Powdery Mildew Pathogens Two reported fungal species Podosphaera xanthii Erysiphe cichoracearum More than 200 powdery mildew samples showed that only Podosphaera xanthii is in the US Our Powdery Mildew Project Determine genetic variation 2
Variation among isolates of powdery mildew fungus Reproductive bodies of Podosphaera xanthii Pathogen Mating Types: 1 and 2 Fungal Characteristics Obligate parasite (biotrophic) Heterothalic (mating types) Sexual state: cleistothecium Asexual state: conidia Feed on epidermal cells Races have been documented Our Powdery Mildew Project Disease Management 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 3
Expected Time for Powdery Mildew in Illinois and Indiana South: around July 15 Central and North: after July 20 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 Effective Management of cucurbit Powdery Mildew Plant resistance Chemical control Powdery Mildew Management Plant resistance Resistant/tolerant cultivars: cantaloupe, cucumber, squash, pumpkin Cucurbits Resistant/Tolerant to Powdery Mildew Crop Cultivar Crop Cultivar Cucumber Carolina Winter Royal Ace Eureka squash, Table Star Thunder acorn Taybelle PM Melon Athena Zucchini Payroll Eclipse Sebring Marygold Pumpkin Aladdin Primo Gladiator Summer squash, yellow Savor Patriot II Sunglo Sunray Majic Lantern Merlin Pure Gold Powdery Mildew Management Chemical control 15 Fungicides available 4
Fungicides for Cucurbit Powdery Mildew Pumpkin & Squash: Aprovia Top (3,7) Fontelis (7) Inspire Super (3,9) Luna Experience (3,7) Luna Sensation (7,11) Merivon (7,11) Microthiol (S) (M) Monsoon (3) Pristine (7,11) Procure (3), Rally (3) Quintec (13) Torino (U6) Toledo (3), Vibe (3) Vivando (U8) Cantaloupe, Cucumber, Watermelon: Aprovia Top (3,7) Fontelis (7) Inspire Super (3,9) Luna Experience (3,7) Luna Sensation (7,11) Merivon (7,11) Microthiol (S) (M) Monsoon (3) Pristine (7,11) Procure (3), Rally (3) Quintec (13) Torino (U6) Vivando (U8) Most Effective Fungicides for Management of Pumpkin and Squash Powdery Mildew Quintec, Procure, Torino Weekly spray of Quintec alternated with Torino or Procure (from the first sign of the disease until the end of August) Other Important Cucurbit Diseases in Illinois and Indiana Phytophthora blight Downy Mildew Bacterial Spot Other Important Cucurbit Diseases in Illinois and Indiana Phytophthora blight Pumpkin fruit infection by P. capsici Cucurbit fruit infection by P. capsici 5
Squash fruit infection by P. capsici Managing Phytophthora Blight of Cucurbits Recommended practices 3 years of crop rotations Seed treatment with Apron XL LS (0.64 fl oz/100 lb seed) Avoid using contaminated water Disk localized infected plants (areas) Fungicide applications (spray) Effective Fungicides for Phytophthora Blight Revus + Kocide-3000 Alt. Orondis Opti (or Ranman or Tanos) + Kocide-3000 Phytophthora Blight in Bean A sanitation problem: disinfest your hands after touching infected fruit and before touching uninfected fruits 6
Other Important Cucurbit Diseases in Illinois and Indiana Downy Mildew Downy mildew on cucumber A pumpkin filed with downy mildew-infected plants Downy Mildew Control, 2015 Leaf infection, Fungicide Severity (%) Control 19.14 a Revus + Kocide 0.51 bcd Alt. Ranman + Kocide Revus 0.14 cd Revus + Kocide 0.84 bcd Revus + Activator-90 0.54 bcd Revus + Kocide + Activ-90 0.04 d Forum 1.30 b-d Downy Mildew Control, 2015 Leaf infection, Fungicide Severity (%) Control21.67 cd 19.14 a Gavel 0.25 cd Omega 0.00 d Presidio 0.15 cd ProPhyt 0.18 cd Ranman 1.23 bcd Ranman + Kocide 0.90 bcd Downy Mildew Control, 2015 Leaf infection, Fungicide Severity (%) Control 19.14 a Ridomil Gold Copper 0.85 bcd Tanos 1.80 bc Tanos + Kocide 2.00 b Zampro 0.15 cd Zing (a new formulation) 0.59 bcd 7
Effective Management of Downy Mildew of Cucurbits Fungicides for downy mildew - Revus + Bravo Weather - Omega + Bravo Weather - Orondis Ultra + Bravo Weather - Orondis Opti Other Important Cucurbit Diseases in Illinois and Indiana Bacterial Spot Collapse of pumpkin fruit infected by Xanthomonas cucurbitae Bacterial spot of pumpkin Our Project on Bacterial Spot A disease of pumpkins and winter squash Pathogen survives more than 24 months in the field Pathogen survives more than 20 months in seeds Seed-borne inoculum can be eradicated by hot-water Our Project on Bacterial Spot Seed-borne inoculum can be eradicated by HCl No resistant cultivar is available Crop rotation of > 2 years Chemical control: Dithane-M + copper + Regalia See the handout 8