The latest Arizona Vegetable Integrated Pest Management Update from the University of Arizona (UA) Cooperative Extension in Yuma, Ariz. released Aug. 22, 2012.
Bagrada bug management tips in desert-grown cole crops
By John Palumbo, UA Research Scientist and Extension Specialist
In anticipation of the fall produce season, now is a good time to think about Bagrada bugs. During the summer, there have been a few reports of adult Bagrada bugs in cotton, alfalfa, sudangrass, and weeds. Bagrada were found in sudangrass fields in the Yuma Valley last week.
I observed feeding signs on early cauliflower in the Gila and Dome Valleys this week. One pest control adviser (PCA) reported one or two adults on early transplants. The level of infestation one might expect as planting starts to increase next week is anyone’s guess.
In untreated broccoli and cabbage plantings at the Yuma Agricultural Center over the past two years, Bagrada didn’t begin to build on crops until late September. In 2010, large populations showed up at the onset of the planting season in early September.
What should PCAs expect this season? I can’t say for sure. Do not become complacent just because you aren't finding any Bagrada on the first sets. It would be wise to assume the insect will eventually show up in some intensity in some acreage and you should prepare accordingly.
Preliminary research and anecdotal observations in fields conducted over the last two years suggest that direct-seeded and transplanted crops are most susceptible to Bagrada bug infestations during stand establishment (cotyledon to the fourth-leaf stage).
It doesn’t take a large number of Bagrada adults to cause significant stand losses and crop injury.
Monitoring for Bagrada at stand establishment should focus on fresh feeding signs on new plant tissue, particularly before 9:00 a.m. before adults become active. If fresh feeding signs and/or adults in young stands are found, control should be initiated.
This can include chemigation with pyrethroids, and contact insecticides (pyrethroids, Lannate, Lorsban) once stands are lined out and the irrigation pipe is pulled.
After stands are established and the plant size increases up to the two-to-three leaf stage or on tagged transplants, PCAs may consider alternating to dinotefuron (Venom/Scorpion) to protect plants from Bagrada feeding. This neonicotinoid also provides the knockdown of adult whiteflies and nymphs.
More information on Bagrada bug management on fall cole crops can be found in this Veg Update link - Bagrada Bug Management Tips for the Low Desert.
Click this link to listen to John.
Contact Palumbo: (928) 782-3836 or [email protected].
Plant-derived chemicals as disease inhibitors
By Mike Matheron, UA Extension Plant Pathologist
Chemicals are indispensible tools in the ongoing effort to minimize crop losses due to plant diseases. Various active ingredients within fungicides are especially useful for managing diseases caused by many fungal plant pathogens.
Although often not recognized, various substances produced by plants and present before infection can enable plants to defend themselves against potential plant pathogens. The level of defense against potential plant pathogens can range from various levels of resistance to outright immunity.
A variety of chemical substances are present on the surfaces of plants including leaves, stems, fruit, seeds and roots. Chemicals with antimicrobial properties include phenolic compounds, tannins and fatty-acid like materials.
Experiments have shown that some of these compounds have an inhibitory action on certain plant pathogens.
As an example, toxic exudates on leaves of a specific variety of sugar beet are present in sufficient concentrations to inhibit spore germination of certain fungal pathogens. Another compound in certain types of tomato plants was shown to impart resistance to powdery mildew by inhibiting spore germination.
Additionally, proteins and enzymes on plant surfaces can inactivate pathogen enzymes essential for disease development. These preformed compounds, together with various types of structural plant disease defenses, often drive resistance to diseases in plants.
Even if these plant derived chemical and structural disease defense systems are not sufficient to totally prevent disease, the systems, along with disease management tools applied by growers, contribute to the overall level of disease suppression obtained on a particular crop.
Click this link to listen to Mike's Update.
Contact Matheron: (928) 726-6856 or [email protected].
By Barry Tickes, UA Area Agriculture Agent
Balan (Benefin) is one of three principal herbicides used on lettuce. Our surveys indicate that fewer acres are treated with Balan than are treated with Kerb or Prefar. Balan is commonly used in combination with one or both of these.
Balan is in the dinitroaniline herbicide family that includes some of the most important herbicides used worldwide.
The first dinitroaniline herbicide registered was Trifluralin (Treflan) in 1960. Within the next 10 years, others in this family including Pendemethalin (Prowl), Ethalfluralin (Sonalan, Curbit) and Oryzalin (Surflan) were registered.
These herbicides are typically bright yellow and were originally discovered when evaluating chemicals for dyes.
Unlike Kerb and Prefar, Balan is normally put on before beds are listed and shaped. It is fairly volatile, will evaporate into the air, and is also subject to photodegradation. Due to this, it is normally mechanically incorporated within hours of application. The label suggests four hours although volatility will vary with moisture and temperature.
Balan adheres well to the soil and is difficult to incorporate with water. It should be mechanically incorporated. Shallow incorporation will help to avoid diluting it too much in the soil. Flat incorporation, listing, and shaping make it difficult to concentrate this herbicide in the bed top where it needs to be.
It is tempting to mulch Balan into the bed top after listing. This will improve weed control but greatly increases the chance of crop injury.
Like other dinitroanaline herbicides, Balan is good on many grasses and will control some broadleaf weeds including pigweed and lambsquarters but is less consistent on broadleaves. The application rate of the DF formulation varies little from 2.0 pounds per acre on coarse textured soils to 2.5 pounds per acre on finer textured soils.
Balan moves very little in either the soil or the plant. It stops cell division in roots and shoots that come in contact with it. Roots that are out of the zone where the herbicide is concentrated will grow normally.
Although this herbicide moves very little in the crop or weeds, crop injury can often be seen in the first true leaves which appear stunted and distorted. Balan breaks down by anaerobic degradation or in areas where water stands and oxygen is limited. On well drained soil it will normally persist for four to six months.
Click this link to listen to Barry.
Contact Tickes: (928) 580-9902 or [email protected].
Flower beetles in fall crop stand establishment
By Ta-I Huang, UA post doc research associate
Last week, a cauliflower transplant tray was received from a local grower for pest and damage symptom diagnosis. After careful inspection, no damage from insects or pathogens was present on the plants. The tray was placed outside in the shade for several hours to let the soil dry down for inspection of the soil and roots.
Although no root damage was observed, tiny fast-moving beetles resembling ants were found in great numbers all over the tray. The beetles had moved onto the trays from the surrounding habitat.
Specimens were collected and images were sent to Margarethe Brummermann at the University of Arizona Insect Collection who identified the bugs as flower beetles in the family Anthicidae. The common name for these beetles is the “ant-like flower beetle.”
There are approximately 3,500 species of Anthicidae in the world. Most live in tropical and subtropical regions. It is a large group but still poorly studied. During the last 15 years, more than 300 new species and several new genera were discovered and described worldwide.
The role of ant-like flower beetles is not completely understood. The insect is present in various habitats from high mountains to rainforest to the desert. The beetle can be found around flowers, leaf litter, soil, rotten wood, or a tree canopy.
In North America, the beetle is often brown or black with red or yellow markings that range in size from 1.5 to 2.0 mm in length. Adults and larvae of ant-like flower beetles are omnivorous, known to consume small arthropods, eggs, pollen, fungi, or whatever can be found.
Some groups are used as a biological control agent as the role of egg predator on many agricultural pests.
If PCAs or growers encounter this type of beetle in the field, do not target sprays for control. The beetle may provide some level of natural control of other soil pests in a crop system.
If any beetles or other insects are found on the soil during stand establishment in fall crops, collect a few and bring them to the UA in Yuma for identification.
For more information, click on this link: http://tolweb.org/Anthicidae/10323.