Pecan Diseases Flashcards
Where are pecans grown in the US?
South-Eastern USA
What pecan disease is similar to a zinc deficiency?
Bunch disease
What is the causal agent of pecan bunch disease?
phytoplasma
How is pecan bunch disease naturally spread?
unknown
Where is bunch disease phytoplasmas located in the pecan plant?
Phloem only
Can pecan bunch disease be cultured in the lab?
No
What insects transmit pecan bunch disease?
leafhoppers
treehoppers
psyllids
What symptoms does pecan bunch disease show?
witches broom
What is the easiest way to diagnose pecan bunch disease?
affected limbs shoot earlier in the early spring (7-14 days)
How is pecan bunch disease controlled?
removal of infected shoots
Use Stuart as a cultivar
What is the single most important pecan disease?
Scab
What regulates the severity of pecan scab disease?
frequency of summer rains
What is Fusicladosporium effusum?
pecan scab
Where does pecan scab occur on the plant?
leaves, fruit shucks, green twigs
What part of the pecan plant is most susceptible to scab?
young tender tissues
What are symptoms of pecan scab?
small black spots on lower leaf surface
When is pecan scab most damaging?
on shuck infections between fruit onset and shell hardening
When does pecan scab secondary white fungal growth occur?
Late august
What do severe infections of apple scab result in?
fruit death
Where does pecan scab overwinter?
on tissues infected the previous year
Are inoculum in the tree or on the ground more important for pecan scab?
in the tree
When does the release of pecan scab conidia peak?
late morning hours
How many hours of wetness is needed for significant leaf infections of pecan scab?
12
How can pecan scab be controlled?
resistant cultivars
fungicides
How can resistance to fungicides be avoided?
Use multiple fungicides with more than one mode of action
Apply as a preventative
Minimize the number of applications
