|
|
How to Manage Pests
UC Pest Management Guidelines
Cucurbits
Spider Mites
(Reviewed 12/09,
updated 12/09)
In this Guideline:
|
|
|
Examine leaves with a hand lens for spider mites.
Frequently, infestations include a mixture of spider mite species. Adult mites
are about 0.06 inch in length, have four pairs of legs, are greenish to pink or
cream colored, and have various sized black spots on the body. Under warm
conditions spider mites move rapidly within the colony area. Spider mites have
four stages of development: (1) the oval, somewhat translucent egg; (2) a six-legged
translucent immature stage;
(3) an eight-legged
immature stage; and (4) the eight-legged adult
stage. A generation may pass in as
few as 5 to 7 days in mid-summer, or in a month during cool periods. Spider
mites produce webbing that is often filled with cast skins, dust, and other
debris.
Mite feeding results in the destruction of chlorophyll; leaves
become pale, stippled, and in later stages of infestation dry up and die. Loss
of color is pronounced on the under surface of leaves before it becomes
apparent on the upper side. Light infestations can be tolerated, but when
heavy, can result in lowered yield and reduced quality of fruit.
Biological control is an important component of mite management.
Take measures to ensure the survival of predators and parasites.
Biological Control
Several predators play an important role in regulating spider mite
populations, including the western
predatory mite (Galendromus [Metaseiulus]
occidentalis), sixspotted thrips (Scolothrips
sexmaculatus), western flower
thrips (Frankliniella occidentalis),
lady
beetles (Stethorus sp.),
minute pirate bug (Orius tristicolor), and lacewing larvae (Chrysoperla
carnea). The western predatory mite
is the same size as spider mites but lacks spots and ranges in color from cream
to amber red. It is available commercially, but research has not been done on
the effectiveness of releasing these predators in cucurbits. Sixspotted thrips
and western flower thrips are also effective predators, but naturally occurring
populations of these insects generally do not develop to high enough levels
that they can provide significant control until damage has already taken place.
Both species are tiny, slender insects about 1 mm or less in length. Sixspotted
thrips has three dark spots on each forewing; western flower thrips ranges in
color from clear lemon yellow to dark brown. Monitor western predatory mites
and the two species of thrips to determine if they are present in the field and
their relative population density in comparison with pest mites.
Cultural Control
Minimize dust and encourage naturally occurring predators and
parasites by limiting chemical rates and the number of applications. Control field
bindweed growing in or at the edges of
a cucurbit field. Good water management increases plant tolerance to these
pests. After runners are 14 inches long, natural enemies such as sixspotted
thrips or predaceous mites usually control pest mite populations.
Organically Acceptable Methods
Biological and cultural controls and sulfur sprays (not for use on
sulfur sensitive varieties) are acceptable to use in an organically certified
crop.
Monitoring and Treatment Decisions
No threshold is established, but when buildup is observed either
spot or completely treat the field before webbing occurs or before runners are
14 inches in length, providing no predatory thrips or predaceous mites are
present. After the rows close over, ground equipment cannot get in the field
and chemical treatment must be applied by aircraft. Such treatments are less
effective because it is difficult to obtain good coverage by aircraft.
| Common name |
Amount/Acre |
R.E.I.+ |
P.H.I.+ |
| (trade name) |
|
(hours) |
(days) |
|
| The following materials are listed in order of usefulness in an IPM program, taking into account efficacy, pesticide registrations, information related to natural enemies and honey bees, and environmental impact. Not all
registered pesticides are listed. Always read label of product being used. |
| |
| A. |
BIFENAZATE |
| |
(Acramite) 50WS |
0.75–1 lb |
12 |
3 |
| |
MODE OF ACTION GROUP NUMBER1: 25 |
| |
| B. |
ABAMECTIN* |
| |
(Agri-Mek) 0.15EC |
8–16 fl oz |
12 |
7 |
| |
MODE OF ACTION GROUP NUMBER1: 6 |
| |
| C. |
DICOFOL |
| |
(Kelthane) 50 |
1.25 lb |
48 |
2 |
| |
MODE OF ACTION: UNC |
| |
COMMENTS: Add a proper sticker spreader. Do not make more than
2 applications/season. Do not feed treated vines, forage, or crop residues to meat or dairy animals. |
| |
| D. |
SULFUR# |
15–20 lb |
24 |
0 |
| |
MODE OF ACTION: Unknown. An inorganic insecticide. |
| |
COMMENTS: Do not apply when temperature exceeds 95°F or use on sulfur-sensitive varieties. Not effective on Pacific mites. |
| |
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Cucurbits
UC ANR Publication 3445
Insects and Mites
E. T. Natwick, UC Cooperative Extension, Imperial County
J. J. Stapleton, UC IPM Program, Kearney Agricultultural Center, Parlier
C. S. Stoddard, UC Cooperative Extension, Merced & Madera counties
Acknowledgment for contributions to Insects and Mites:
R. L. Coviello, UC Cooperative Extension, Fresno County
L. D. Godfrey, Entomology, UC Davis
C. B. Fouche, UC Cooperative Extension, San Joaquin County
C. G. Summers, Entomology, UC Davis/Kearney Agricultural Center, Parlier
J. B. LeBoeuf, AgriData Sensing, Inc., Fresno
M. Murray, UC Cooperative Extension, Colusa/Glenn counties
Top of page
|
