|
|
How to Manage Pests
UC Pest Management Guidelines
Nectarine
Brown Rot Blossom and Twig Blight
Pathogens: Monilinia fructicola, occasionally Monilinia laxa
(Reviewed 6/06,
updated 6/06)
In this Guideline:
|
|
|
SYMPTOMS
Young blossom spurs and
associated leaves collapse to form shoot blight. Gum exudes at
base of infected flowers. Cankers on blighted twigs have tan centers with dark
margins. Gray brown spore masses form on diseased flower parts and twig cankers under high humidity.
Monilinia fructicola overwinters on mummified fruit that either fall to the ground in late fall or early winter, or remain in the
trees. In spring, apothecia form on mummies that are on the ground; these apothecia release ascospores at
the same time as the trees bloom. Ascospores serve as primary inoculum for brown rot in
many orchards. Mummies in the trees as well as those on the ground may also
produce conidia, which may serve as the primary source of inoculum in some
years. Twig lesions apparently do not produce spores.
Although all flower parts except the sepals are susceptible to
infection by M. fructicola, only
infection of the stamens leads to the development of blossom and twig blight.
Bloom sprays to reduce blossom and twig blight help minimize loss to
ripe fruit rot at
harvest. Removal of remaining fruit from trees soon after harvest will help
reduce inoculum the following spring.
Chemical Control
Make a treatment at 20 to 40% bloom and
again at 80 to 100% bloom if heavy rainfall or other conditions are occurring
that result in high susceptibility to infection. Aerial applications are
generally not as effective as properly applied ground sprays but may be
necessary when the orchard floor is wet. To help prevent development of
resistance to fungicides, be sure to rotate chemicals that have different mode
of action Group numbers.
| Common name |
|
P.H.I.+ |
| (trade name) |
Amount to Use |
(days) |
|
| The following materials are listed in order of
usefulness in an IPM program, taking into account efficacy. When choosing a
pesticide, also consider information relating to environmental impact.
|
| |
| A. |
PROPICONAZOLE |
| |
(Bumper, Orbit) |
4 oz/acre |
0 |
| |
MODE OF ACTION: A DMI (Group 3)1
triazole fungicide.
|
| |
| B. |
TEBUCONAZOLE |
| |
(Elite) 45WP |
4–8 oz/acre |
0 |
| |
MODE OF
ACTION: A DMI (Group 3)1 triazole fungicide.
|
| |
COMMENTS: Do not apply more than 3 lb/acre/season. |
| |
| C. |
FENBUCONAZOLE |
| |
(Indar) 75WSP |
2 oz/acre |
|
| |
MODE OF ACTION: A DMI (Group 3)1
triazole fungicide.
|
| |
COMMENTS: Do not apply more than 1 lb/acre/season. |
| |
| D. |
IPRODIONE |
| |
(Rovral) 4 |
1–2 pt/acre |
|
| |
MODE OF ACTION: A dicarboximide (Group 2)1
fungicide.
|
| |
COMMENTS: Addition of a narrow range oil (superior, supreme)
at 1–2% increases the effectiveness of this material. May not be used after petal fall. |
| |
| E. |
PYRACLOSTROBIN/BOSCALID |
| |
(Pristine) |
10.5–14.5 oz/acre |
|
| |
MODE OF ACTION: A Qol (Group 11)1 and carboxamide
(Group 7)1 fungicide.
|
| |
COMMENTS: To reduce the potential for resistance, do not make
more than 5 applications of this or other Group 11 or 7 fungicides per season. Do not make more than 2 sequential applications of this product. |
| |
| F. |
THIOPHANATE METHYL |
| |
(Topsin-M) 70WP |
8 oz/100 gal water |
1 |
| |
MODE OF ACTION: A MBC (Group 1)1
thiophanate fungicide.
|
| |
COMMENTS: Strains of Monilinia fructicola resistant to thiophanate methyl are common,
especially in the Sacramento and northern San Joaquin Valleys. If resistance
has occurred in your orchard, do not use this fungicide; otherwise, one
application at early bloom is usually sufficient. If brown rot is severe, or
an extended bloom period is accompanied by rainfall, make a second application using a fungicide with a different Group number. |
| |
| G. |
CYPRODINIL |
| |
(Vangard) WG |
5 oz/acre |
|
| |
MODE OF ACTION: An AP (Group 9)1 fungicide. |
| |
COMMENTS: Do not apply more than 10 oz/acre/year. |
| |
| H. |
FENHEXAMID |
| |
(Elevate) 50 WDG |
1–1.5 lb/acre |
0 |
| |
MODE OF ACTION: A hydroxyanilide (Group 17) 1
fungicide.
|
| |
COMMENTS: Avoid making more than 2 consecutive applications of this material. |
| |
| I. |
MYCLOBUTANIL |
| |
(Rally) 40W |
2.5–6 oz/acre |
0 |
| |
MODE OF ACTION: A DMI (Group 3)1
triazole fungicide.
|
| |
COMMENTS: Do not apply more than 3.28 lb/acre/season. |
| |
| J. |
AZOXYSTROBIN |
| |
(Abound) |
12.3–15.4 fl oz/acre |
0 |
| |
MODE OF ACTION: A Qol (Group 11)1 fungicide. |
| |
COMMENTS: Do not apply more than two applications before alternating with a fungicide that has a different mode of action. |
| |
| K. |
CHLOROTHALONIL |
| |
(Echo 720) |
3.125–4.125 pt/acre |
|
| |
(Bravo Ultrex DF) |
2.8-3.8 lb/acre |
|
| |
(Bravo Weather Stik) |
3.125–4.125 pt/acre |
|
| |
MODE OF ACTION: A multi-site contact (Group M5)1
chloronitrile fungicide.
|
| |
COMMENTS: Do not use with or closely following oil sprays. May not be used after jacket split. |
| |
| L. |
CAPTAN 50WP |
| |
(various products) |
2 lb/100 gal water (dilute spray) |
|
| |
MODE OF ACTION: A multi-site contact (Group M4)1
phthalimide fungicide.
|
| |
COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays. |
| |
| |
|
More information on nectarine fungicides
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Nectarine
UC ANR Publication 3451
Diseases
W. D. Gubler, Plant Pathology, UC Davis
J. E. Adaskaveg, Plant Pathology, UC Riverside
Acknowledgment for contributions to the diseases section:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
Top of page
|
