The Arizona Vegetable Integrated Pest Management Update from the University of Arizona (UA) Cooperative Extension in Yuma, Ariz. released Aug. 7, 2013.

Insect pests at stand establishment in fall melons and produce

By John Palumbo, UA research scientist and Extension specialist

Growers have begun planting fall melon crops and produce planting is a few weeks away. Pest control advisers are likely to find many insects with the potential to cause serious economic losses to seedling crops during stand establishment.

These include flea beetles, crickets (sometimes grasshoppers), darkling and rove beetles, and saltmarsh caterpillars. These insects have chewing mouthparts. Most can consume large amounts of leaf tissue in a short time.

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Seedling crops at the cotyledon stage are most susceptible to these pests. Feeding by large numbers can devour much of the cotyledons or outright kill small plants.

If left uncontrolled, larger seedling plants (2-4 leaf stage) can sustain significant feeding damage on terminal growing points or newly emerged leaves. Not only can this feeding stunt plant growth, it can result in the lack of uniformity and maturity at harvest.

Host sources of flea beetle, cricket and ‘wooly worm’ infestations include numerous summer crops (e.g., sudan grass, cotton, and alfalfa) and a large host of weeds (e.g., purslane).

Experience suggests that melon fields planted adjacent to these crops and weedy areas are at a high risk of these seedling pests, particularly flea beetles. As these summer host plants are harvested or terminated over the next few weeks, seedling pests typically move to the next available host crop - lettuce, cole crops, and melons.

Fortunately, many registered insecticide alternatives are available that can be applied via sprinkler chemigation (i.e., pyrethroids) or foliar sprays (i.e., Lannate, neonicotinoids) that can cost effectively minimize the insect abundance and damage to emerging crops.

For more information on insect pests of leafy vegetables and melons at stand establishment, click on thislink.

Listen to Palumbo's update

“Remember, when in doubt - scout.”

Contact Palumbo: (928) 782-3836 or jpalumbo@ag.arizona.edu.

Plant pathogen survival in the desert

By Mike Matheron, UA Extension Plant Pathologist

People can escape the desert heat by finding refuge in air conditioned buildings or can obtain food from any number of sources at any time. On the other hand, plant pathogens must survive high temperatures and the lack of food by employing other tactics.

Some plant pathogens can thrive at temperatures common in the desert during the summer and cause disease on plants growing at that time. However, most others cannot function at temperatures much above 90 degrees Fahrenheit.

To survive inhospitable temperatures or the lack of a host to feed, fungal pathogens often produce thick-walled durable spores or other structures that will allow the organism to survive hostile environments in a dormant state.

The visible dark-colored sclerotia produced by the lettuceSclerotinia pathogens are such structures. Much smaller sclerotia and thick-walled spores facilitate long-term survival of the soil-borne pathogens Rhizoctonia and Fusarium, respectively.

In comparison, bacterial plant pathogens do not have recognized survival structures but can subsist in a reduced metabolic state on, in, or near living or dead plant tissue.

Virus pathogens also cannot make resistant structures so survival usually occurs in living plants or vectors. These plants can include weeds or cultivated crops that do not express disease symptoms yet serve as sources of virus to visiting insect vectors.

Finally, nematode survival stages can include eggs and certain larval forms. Many of the cultural disease management methods employed now are effective which disrupt the normal survival capability of these plant pathogens.

Listen to Matheron's Update.

Contact Matheron: (928) 726-6856 or matheron@ag.arizona.edu.

If you can’t beat them – eat them

By Barry Tickes, UA area agriculture agent

Many plants now regarded as weeds were brought here or introduced for landscape or food many years ago and now grow wild. However, some are natives found here for thousands of years.

One of the native plants currently in season and available in grocery stores and farmers markets is the prickly pear cactus. It grows wild and in abundance here and throughout arid regions of the western hemisphere.

Prickly Pear is one of more than 200 species of the Opuntia genus and Cactaceae or cactus family.

The most common edible species is the India fig opuntia(O. ficus indica). It has been a staple of the Mexican and Central American diet for thousands of years. It has three edible parts - the pad or nopal which is peeled and treated like a vegetable; the pedals used in salads; and the ‘pear’ used as a fruit.

Nopales are thought to be good for treating diabetes, high cholesterol, and hangovers.

The following video is a demonstration on how to peel the pads. Please click hereto watch video.

Click the link to listen to Barry.

Contact Tickes: (928) 580-9902 orbtickes@ag.arizona.edu.

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