[nafex] RE: Raspberries

Thomas Olenio tolenio at sentex.net
Sat Jul 15 17:07:15 EDT 2000


Hello,

This link and quaote may help regarding your Latham problem;

http://ssfruit.cas.psu.edu/chapter7/chapter7h.htm

Phytophthora Root Rot
Phytophthora root rot now is regarded as a major cause of declining
red raspberry plantings. Blackberries and black raspberries appear to
be less susceptible than red or purple raspberries. Wet soil
conditions favor the development of the disease, and it can be
observed often in low-lying areas of a field. Declining plants
previously diagnosed as suffering from wet feet or winter injury
usually are infected by this root rot.

Symptoms

Leaves of infected canes yellow prematurely or appear scorched along
the margins and between the veins. Infected canes have weak lateral
shoots and are stunted. The root systems of affected canes must be
examined to diagnose Phytophthora root rot. Infected roots have a
characteristic red-brown color, whereas healthy roots appear white. A
distinct line can be seen where infected and healthy tissue meet.

Disease Cycle

Phytophthora root rot is caused by at least eight different species of
soilborne fungi belonging to the genus Phytophthora. Resistant spores
of the fungus can persist in the soil for a number of years. They are
resistant to environmental extremes and chemicals. The fungus requires
high levels of moisture and cool temperatures for reproduction. The
fungus infects plants in the spring and during the onset of dormancy.

Disease Management Method for reducing chemical inputs
Good soil drainage and proper cultivar selection are necessary for
controlling Phytophthora root rot. Plant all brambles in well-drained
soil or in raised bed plantings. Highly susceptible cultivars include
Titan, Ruby, Hilton, Canby, Taylor, Reveille, and Festival. Latham and
Newburgh are the least susceptible and are the safest choices. No
raspberry is immune, although black and purple raspberries are

Hope this helps.

Regards,
Tom

--
Thomas Olenio
Ontario, Hardiness Zone 6a


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