Pheromone/Sticky Trap Monitoring Network
Western Flower Thrips in Spring Produce Crops
Western flower thrips are now beginning to increase on produce crops throughout
the area. They have slowly been increasing in the Yuma Valley, and should likely
continue to increase as the days grow longer. Based on historical data, if temperatures
remain moderate and rainfall is light we can expect thrips numbers to reach very
high levels by the mid-March. Another factor PCAs should be concerned with this
time of the year is thrips "bioconcentration" which occurs each year in late February
and March as lettuce acreage declines. This could be especially important this season
since the abnormally warm temperatures appear to be pushing lettuce harvests ahead
of schedule relative to years past. Each time a lettuce field is harvested and disked,
adult thrips populations disperse from these areas into the next available lettuce
field. This is generally coincident with our seasonally warm temperatures that are
suitable for thrips development. As the number of lettuce acres becomes reduced
near the end of the season, this creates a bottleneck effect that concentrates high
numbers of thrips adults on the remaining fields under production. This can often
make chemical control very difficult, particularly in March, as thrips adults may
continually re-infest fields following spray applications. Furthermore, by mid-March
when most of the lettuce production is finished, these populations can pose a threat
to seedling cotton. Note: the key to preventing thrips from significantly scarring
leafy vegetable plants is to prevent immature populations from becoming established.
For more information on the identification, biology, ecology and management of thrips
on desert produce please visit the links:
Western Flower Thrips
Thrips Control Chart
Click picture to listen to John’s update
To contact John Palumbo go to: email@example.com
Downy Mildew on Spinach and Related Plants
Spinach is a member of the plant family Chenopodiaceae, which also contains the
crop plants beets and Swiss chard as well as weeds such as nettleleaf goosefoot
and lambsquarters. Downy mildew, caused by the oomycete pathogen Peronospora farinosa,
which exists as different races or subtypes, can develop on all of these plants.
An important question for spinach growers is this: can isolates of the pathogen
that cause downy mildew on beets, Swiss chard, or weed hosts cause downy mildew
on spinach? Monterey County, California Farm Advisor Steve Koike and colleagues
conducted research to answer this question. Isolates of the pathogen from nettleleaf
goosefoot, lambsquarters, beet and Swiss chard were each used to inoculate spinach.
The result: no disease development. In a separate experiment, the downy mildew pathogen
from spinach was used to inoculate nettleleaf goosefoot and lambsquarters. The result
again was no disease development. The bottom line is that spinach growers need not
worry about related Chenopodiaceae such as nettleleaf goosefoot, lambsquarters,
beets or Swiss chard as potential sources of inoculum for their spinach crop. Even
though the bluish-purple evidence of the pathogen on the underside of leaves is
similar in appearance on all of these plants, the particular isolates of the downy
mildew pathogen have very specific and limited host ranges.
Click picture to listen to Mike's update
Summer Annual Grass Identification
It is better to be a month early when applying preemergence herbicides for summer
annual grass control than it is to be a day late. They have begun to emerge so don’t
wait. It is important to know which grass(s) that you have but that is not possible
without prior knowledge when making preemergence applications. There are more than
25 annual grass species that are found here during the summer although only about
10 are common. Most of these look very similar at early growth stages and identification
can be difficult. There is a tendency to lump them all together and call them water
grass, jungle rice barnyard grass or several other names. There are differences
between them, however, and it is important to accurately identify them at early
growth stages. This is important because many of them respond differently to herbicides
and have different growth habits. For example, sprangletop is only controlled by
the highest rates of Select (clethodim) and generics of this herbicide and missed
by all of the other selective postemergence herbicides like Poast and Fusilade and
sandbur is tolerant to all of them. By the same token, sandbur and sprangletop can
over winter, come back from crowns and not be controlled by preemergence herbicides
applied in the spring while most other summer annual grasses die in the winter and
the seed can be controlled with herbicides in the spring. There are just 6 genera
and 12 species of summer annual grass that are common here. These include echinochloa
(water grass and barnyard grass), leptochloa
(red sprangletop and mexican sprangletop),
(southwestern cupgrass and prarie cupgrass), cenchrus
(field sandbur and
red sandbur), setaria
(green foxtail and yellow foxtail), and chloris
grass and truncate finger grass). A power point presentation can be found by clicking
Summer Annual Grass ID
which contains pictures and descriptive characterics
of each of these species.
Click picture to listen to Barry
Areawide Insect Trapping Network
Mar 5, 2014
To contact John Palumbo go to: firstname.lastname@example.org
Results of pheromone and sticky trap catches can be viewed
Corn earworm/Tobacco budworm:
Corn earworm activity continues to remain steady
in most trapping areas, and a particularly sharp increase in flight activity was
observed in the south Yuma Valley.
Cabbage looper/Beet armyworm:
Beet armyworm activity continues to increase,
and cabbage looper moth activity remains steady in all locations this week, particularly
Adult activity remains negligible in all areas.
Thrips numbers are beginning to increase to seasonal highs as lettuce
acerage begins to steadily decline.
Winged aphids remain steady over the past two weeks in all traps.
Alate green peach aphid numbers were the dominant aphid species. Cabbage aphid alates
were also observed.
The Vegetable IPM Updates Archive page provides links
to updates from previous weeks.
The Vegetable IPM Video Archive page contains a collection
of educational videos from current research work in vegetable crops by University
of Arizona Researchers.
For questions or comments on any of the topics please contact Marco Pena at the Yuma Agricultural Center.
College of Agriculture, The University of Arizona, Tucson, AZ.
document located at: http://cals.arizona.edu/crops/vegatables/advisories/advisories.html
Copyright © 2001 University
College of Agriculture and Life
Webmaster: Al Fournier (email@example.com)