Ash/Oak Anthracnose Control: Raking and destroying leaves Spray 3 times: 1. When buds begin to swell, before they break 2. When buds show green tips 3. When the leaves are ½ grown (Only necessary on high value trees in areas of recurring heavy infection) Small purple spots: signs of initial infection Necrotic areas of advanced infection
Ash/Oak Anthracnose Before I give you this information I need to give you the typical disclaimer that is always associated with providing information about chemicals and their application – which I am sure you have heard before. Always read the label and mix and apply chemicals precisely in accordance with the manufacturers label using the proper equipment and protective gear. Spray 3 times: 1. When buds begin to swell, before they break (lime sulfur) 2. When buds show green tips (chlorothalonil) 3. When the leaves are ½ grown (chlorothalonil)
Black Rot/Frog Eye Leaf Spot (Botryosphaeria obtusa) University of Georgia, bugwood M. Kangas, NDFS Spores develop and are dispersed during cool (≈70˚F) wet weather throughout the growing season.
Black Rot/Frog Eye Leaf Spot Fall: good sanitation practices Rake up and destroy/bury infected leaves Remove mummified apples Prune out cankers using proper technique sterilization between cuts Good cultural practices usually eliminate the need to apply fungicide Photos by Clemson U, UGA, bugwood
Black Rot/Frog Eye Leaf Spot New Shoot Spray/after bloom spray: When new shoots are 1- to 2-inches long, also when new shoots are 6- to 8-inches long. Guidelines for larger-scale fruit production: Fungicide per Gallon of Water. 3.0-4.0 tbsp Mancozeb F1 + 1.0 tbsp Sevin 80S + 4.0 tbsp Immunox + sulfur 2.0-4.0 tbsp From: http://www.caf.wvu.edu/kearneysville/vadisbul.pdf Immunox (not Immunox plus) itself may provide sufficient control for the homeowner
Cytospora (not just a problem on spruce) A. Bergdahl, NDFS M. Kangas, NDFS
Cytospora Maintain good plant health cytospora is a stress-related disease Prune out and destroy cankers and dead branches as soon as they occur (sterilize tools in between cuts!) Prevent cytospora by properly spacing spruce plantings encouraging air flow Many trees are affected by this disease (apple, ash, aspen, birch, cottonwood, elm, maple, peach, spruce, willow).
Cytospora on quaking aspen Bill Jacobi, CO State
Cytospora Fungicide applications are generally not effective treatments for canker diseases.
Rhizosphaera (Rhizosphaera kalkhofii) and Stigmina (Stigmina lautii) healthy diseased More defined margins ‘Feathery’ Margins M. Kangas, NDFS
Rhizosphaera and Stigmina At planting: allow adequate space, plant healthy stock Spray fungicide at 2 times for rhizosphaera Spring: when needles are 50% elongated (≈Labor Day) Summer: when needles reach full elongation (≈4 th of July) Chlorothalonil or Bordeaux mixture No published information on the treatment of stigmina Preliminary NDSU studies indicate effectiveness of a treatment regime similar to that for rhizosphaera. The infection period of stigmina appears to be longer than that of rhizosphaera and therefore may require an earlier and later fungicide application to limit damage.
Rhizosphaera and Stigmina Managers will need to determine whether a symptomatic spruce has Rhizosphaera or Stigmina Samples should be submitted to the NDSU Plant Diagnostic Lab for confirmation
Fire Blight (Erwinia amylovora) Disease activity and severity increases with temperature – spread is aided by rain splash. Apple, Cotoneaster, Crabapple, Mountain-ash, Hawthorn, (Rosaceae sp.) M. Kangas, NDFS
Fire Blight Plant resistant cultivars Prune out infected plant parts Sterilize pruning equipment between cuts (denatured alcohol, pine sol®, 1-part bleach/5-parts water solution Early season: Application of antibiotic (streptomycin) may provide early season control
Fire Blight Following hail or mechanical damage: Application of streptomycin may prevent outbreak Follow application guidelines, as they vary among products Prevents canker formation/long-term prolific inoculum source Growing season: Avoid exposure to excess nitrogen Succulent shoot growth is highly susceptible and exacerbates infection. *Chemical applications of streptomycin or copper-based fungicides may provide early-season control of fire blight bacterial infection.