Citrus and Date Palm Specialist - Glenn
My role as extension specialist at the Yuma Agriculture
Center is through a split appointment (60% extension, 40% research) with
responsibility for developing an externally funded applied research and
extension program centered on fruit crop physiology, chiefly with citrus.
My position has existed in Yuma since 1935, and I am the fourth person
to occupy it. Because citrus can be grown in six Arizona counties (trees
are found as far east as Tucson and as far north as Bullhead City), and
the commercial industry is found in four counties, my position has state-wide
responsibility. I also conduct some research in the California desert
citrus growing areas.
|Some of my cooperative work has focused on investigating
ways to improve irrigation and fertilization efficiency while not sacrificing
citrus yield or quality. These projects have included the use of low volume
irrigation systems, in contrast to the traditional flood, and the application
of nitrogen through those irrigation systems in accordance with "Best
Management Practices". Other related projects have included a determination
of the ways to improve the application efficiency of flood irrigation through
the use of soil moisture deficit data. Also, I am testing foliar slow release
nitrogen fertilizers that may lead to more efficient nitrogen application.
| I am also investigating cultural practices that
may be used in improve citrus fruit packout. Packout refers to the combination
of fruit size and quality that leads to the best grower return. In two separate
studies, I am researching the effect of potassium applications on citrus
fruit yields and quality. Plant growth regulators and citrus tree girdling
are two additional cultural practices that I am investigating. Several of
my projects involve orchard floor management. Together with cooperators,
I investigate how traditional disking, non-traditional cultivation methods
and clean culture with herbicides affects plant growth, water usage, fruit
yield and quality, and weed population dynamics. We are also investigating
the effects of clover cover crops on the above parameters.
have also concentrated my efforts on citrus scion and rootstock evaluation
and breeding. Some cultivars that are commonly grown in other citrus growing
areas of the US do not perform well in the desert Southwest. Additionally,
the Arizona citrus industry’s reliance on lemons necessitates a continual
search for new lemon cultivars and rootstocks that are compatible with lemon.
One major study involves the search for a rootstock that is resistant to
brown heartwood rot fungus, Coniophora eremophila. In this work, we wish
to determine why some rootstocks appear to be more susceptible to fungal
invasion than do others.
| My breeding work also is aimed toward developing
new citrus scions or rootstocks that are compatible with lemon. I also evaluate
new deciduous stone fruit and blackberry cultivars for their suitability
to the climate of the low deserts of southern Arizona.
My extension work involves education, chiefly in regards
to citrus. I speak to commercial growers, master gardeners and homeowners
regarding citrus in several locations across the state annually. Additionally,
I write for the local newspaper and appear occasionally on television.
Also, I edit the Arizona Citrus Newsletter, a quarterly publication
that is now on the World Wide Web at http://ag.arizona.edu/aes/yuma-mesa/