Plant Diseases
Rice Diseases in Arkansas
There are at least 20 diseases of rice routinely observed in Arkansas with
most being caused by fungi and a handful considered major problems to rice
production. Major diseases include:
Sheath blight, potentially damaging on about 2/3 of the long-term rice
fields in the state, especially on heavily fertilized semidwarf long-grain rice
varieties. Sheath blight is a very consistent disease, requiring attention each
year. Several hundred thousand acres of rice are treated with sheath blight
fungicides each year in Arkansas.
Blast can be more serious than sheath blight on certain varieties but
is very sporadic, depending on frequent rainfall and moderate temperatures in
the summer which have not been common in recent years. Neck blast can cause
total loss of a susceptible variety under the right conditions. In the mid 80s,
neck blast destroyed whole fields of Newbonnet rice in Arkansas.
Straighthead, the oldest known rice disease in Arkansas, occurs on
certain fields and can cause heavy losses if these fields are not drained and
dried just prior to joint movement. Some varieties are more susceptible than
others but the cause of straighthead is still not clearly understood. Symptoms
that appear identical to straighthead can be induced by application of arsenic
to experimental plots but it is not known if arsenic or some other soil factor
is the cause of natural straighthead in commercial rice fields.
Seed rots and seedling diseases are consistent problems on much of the
April planted rice in Arkansas and on certain minimum tillage fields. While
reducing stand considerably, rice yields may be unaffected by seedling diseases
if the stand is uniform, because modern rice varieties have the ability to
tiller to fill available space and compensate for early stand loss.
Kernel smut has been a problem for many years in Arkansas. Infected
kernels turn to black powder inside causing problems for rice mills, especially
if the rice is used for parboiling. The disease has been a consistent issue in
recent years on certain varieties including LaGrue, Cocodrie, Cypress, Priscilla
and Jefferson in the state. Heavy nitrogen fertilization of these varieties
increases the problem.
Bacterial panicle blight has been a problem in recent years in Arkansas,
mainly on the rice variety Bengal, in years like 1995 with high night
temperatures during July and early August. It has also damaged the variety
Cypress and the new variety Cocodrie is also considered susceptible. LSU
scientists believe this to be the same disease known as bacterial grain rot in
Japan and think that it has been in the U.S. for many years - unnoticed or
misidentified. It has caused major yield losses in Arkansas and other southern
states in certain years.
Other well known rice diseases are sporadic, localized or minor in the state.
They include false smut, stem rot, black sheath rot, scald, scab, aggregate
sheath spot, bordered sheath spot, leaf smut, brown spot and narrow brown spot
among others. In rare instances, any of these diseases have the potential to
cause yield loss under ideal circumstances.
Links
Newsletters
Publications
Below is a list of the nematode related publications available.
Publications can be obtained by contacting the county Extension office or select a title below for an online version of
the fact sheet. Also check our
publications
database for other related publications.
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