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Title: Management of late-maturing peanut varieties
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Title: Management of late-maturing peanut varieties
Physical Description: Book
Creator: Whitty, E. B.
Publisher: Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, University of Florida
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Subject: University of Florida.   ( lcsh )
Spatial Coverage: North America -- United States of America -- Florida
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Bibliographic ID: UF00078709
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
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notis - ANL4387
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    Introduction
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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida








UNIVERSITY OF SS-AGR-75

FLORIDA

EXTENSION
Institute of Food and Agricultural Sciences


Management of Late-Maturing Peanut Varieties1


E. B. Whitty, D. W. Gorbet, and T. A. Kucharek 2

Early maturity in a peanut variety is generally
preferred because the period of time for caring for the
crop is shorter and the time of exposure to pests and
unfavorable weather is reduced. While some varieties
are considered to be mature in as little as 120-125
days after planting, most of the commonly grown
varieties mature in about 135 days. These maturity
dates are based on plantings made near the middle of
the optimum planting period and when conditions are
favorable for seed germination and plant growth. A
variety that matures in 135 days after planting on May
1 may require 150 days or more to mature when
planted on April 1, because the cooler temperatures
slow germination and plant growth.

In recent years, there have been five
late-maturing varieties released by the University of
Florida. Southern Runner was released in 1986,
followed by Florida MDR98 in 1998, C99R in 1999
and Hull and DP-1 in 2002. These are the only late
varieties available to growers, and generally require
150 or more days after planting to reach maturity.

Many of the following suggestions and
comments are based on experiments and observations
with the Southern Runner variety. Thus the
assumptions that are extended to the other four


varieties may not be correct, and if exceptions are
likely, they are noted. Further research and
observations should clarify the specific management
techniques needed for the newer varieties. In the
meantime, it is hoped that the following comments
will be useful to producers of these varieties.

The advantages of these five varieties are
considerable. They are high yielding with resistance
to leaf spot, white mold, and tomato spotted wilt virus
(TSWV), especially DP-1. Southern Runner, Florida
MDR98, and C99R have resistance to rust and it is
likely that DP-1 and Hull also have resistance. Hull
has resistance to CBR and some root knot nematode
resistance. Hull also has the high oleic acid
characteristic. Normally only four applications of a
fungicide would be required to control leaf spot in
these varieties, which is about half the usual number
of applications. Although growers would prefer this
multiple-disease resistance in earlier maturing
varieties, such a combination has yet to be achieved.
These late-maturing varieties should not be assumed
to be entirely low input varieties just because they
have some disease resistance. High yields may
depend on a high level of management.


1. This document is SS-AGR-75, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural
Sciences, University of Florida. First published April 2000. Revised November 2002. Please visit the EDIS Web site at http://edis.ifas.ufl.edu.
2. E. B. Whitty, professor, Agronomy Department; D. W. Gorbet, professor North Florida Research and Education Center, Marianna; and T. A. Kucharek,
professor, Plant Pathology Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville,
32611.The use of trade names in this publication is solely for the publication is solely for the purpose of providing specific information. It is not a guarantee
or warranty of the products named and does not signify that they are approved to the exclusion of others of suitable composition.

The Institute of Food and Agricultural Sciences is an equal opportunitylaffirmative action employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.
For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative
Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean.






Management of Late-Maturing Peanut Varieties 2


To realize the benefits of these varieties, certain
management practices should be considered. These
include special attention to seed quality, crop
rotation, time of planting, planting techniques, and
irrigation. Disease management, weed control,
gypsum application, maturity, and keeping harvested
peanuts separate from all other varieties are also
among the production practices that may need to be
altered for these varieties.

SEED QUALITY

Some of these varieties have exhibited slow
germination and early season growth, especially
under cool conditions. While part of this problem
may be genetic in origin, it is important to plant high
quality seed. The production of high quality seed
includes the application of gypsum prior to pegging
and allowing the kernels to fully mature before
harvest. It has been noted that seed of C99R may not
appear to be mature even though the hull color, as
determined by the hull scrape method, may indicate
maturity. It is possible that shell maturity and kernel
maturity may not occur simultaneously in C99R, so
before digging be sure that about 75 percent of the
kernels have developed a pink or tan color of the skin
or testa, which is indicative of maturity. However,
keep in mind C99R tends to have a lighter color testa
than other varieties.

CROP ROTATION

In some instances, Southern Runner has been
damaged by root knot nematodes. Such damage has
yet to be noted with Florida MDR98 or C99R, while
Hull has some nematode resistance. Since the longer
period to maturity may allow more time for nematode
damage, crop rotations and/or nematicides that help
lower nematode populations would be advisable.
Disease and other pest pressures would normally be
lower if a three to four year rotation with suitable
crops is followed.

TIME OF PLANTING

To enhance seed germination and early growth,
plant these varieties in late April or early May in the
Central Florida locations and early May in the
Panhandle, since more favorable soil temperatures
are likely. Planting should be completed before late


May, because these varieties may not be fully mature
by the time cool temperatures slow growth and
maturity in late October or early November. Cool
temperatures reduce growth and delay maturity. Full
maturity may be impossible under very cool
conditions.

PLANTING TECHNIQUES

Since Southern Runner and Florida MDR98 have
shown low early season vigor, seed should be planted
at a depth as shallow as possible for them to emerge
rapidly. Naturally, the availability of irrigation takes
some of the risk out of shallow planting. Seed should
be placed two inches apart in the row to ensure faster
ground coverage. Even though these varieties have
some resistance to TSWV, you need at least four
plants per foot of row to reduce risks to the virus.
Experiments at Marianna showed that C99R, and to
some extent Florida MDR98, yielded more when
planted in twin rows than in single rows.

IRRIGATION

The late maturing varieties respond favorably to
irrigation. Since they grow over a relatively long
period of time, it is likely that drought stress will
occur at some point during the season. Irrigating in
the early season may help promote early growth of
the plants, but becomes more critical somewhat later
in the season compared to early or medium maturity
varieties.

DISEASE MANAGEMENT

The late-maturing varieties have resistance to
leaf spot, but not immunity. Therefore applications of
fungicides will be needed for satisfactory leaf spot
control. The interval between leaf spot sprays can
also be longer with the resistant varieties (i.e., 21
days), and/or on a weather-based advisory method.
These varieties have good resistance to white mold
but not to limb rot. Abound and/or Folicur should be
used in your spray program to help control
rhizoctonia, especially in a cotton rotation. Florida
MDR98 and C99R have good resistance to TSWV,
but you still should follow the Georgia TSWV index.
Good stands with May plantings are needed.






Management of Late-Maturing Peanut Varieties 3


WEED CONTROL

Weed and crop competition may be reduced
since canopy coverage may be slower with the
late-maturing varieties. Consequently, adequate weed
control may require more herbicides and/or
cultivation than normal. Herbicide application
windows will vary depending on whether an early or
late variety is planted. Due to the lower early season
vigor, including Basagran in the cracking-time
Starfire herbicide application would be advisable to
reduce the potential for foliage damage. On the other
hand, the late-maturing varieties develop slower than
conventional varieties and certain post-emergent
herbicides, such as Classic, can be applied about 2-3
weeks later than for medium maturity varieties. It
would be advisable to delay any such herbicide
application on late-maturing peanuts until they reach
the same physiological stage of growth as for use on
conventional varieties.

GYPSUM APPLICATION

Kernels of Florida MDR98, C99R and Hull
approach the size of virginia types. Consequently,
application of gypsum is advisable, not only if the
peanuts are being grown for seed, but also because of
pod and kernel size. Large-seeded peanuts generally
require more gypsum than small-seeded varieties. It
is critical that gypsum be used on fields that are being
grown for seed production.

MATURITY

As indicated under the above Seed Quality
section, the late-season varieties should be mature
before harvest. There may be a tendency to harvest
them before maturity. Use the hull scrape or peanut
maturity profile method to initially determine
maturity, but be sure that about 75 percent of the
kernels are showing a good pink color, which would
confirm that they are mature. On many farms, cotton
harvest may need to begin before the late-maturing
varieties are mature. Do not plant these varieties if
there is likelihood that they will be harvested early to
facilitate the cotton harvest.


MAINTAINING SEPARATION AT
HARVEST

There are no indications that Florida MDR98,
C99R, Hull and DP-1 cannot be co-mingled with
other runner varieties for shelling and processing. On
the other hand, Southern Runner should be kept
separate so that specific techniques and settings for
the variety can be followed in shelling and
blanching.

SUMMARY

At this time, it is expected that insect control and
other production practices for the late-maturing
varieties would be similar to those used for
conventional varieties.

To take advantage of high yield potentials, lower
production costs, and less potential loss to diseases,
late-maturing varieties would be good choices for
many farmers. However, production practices
specific for these varieties should be followed in order
to realize these benefits.




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