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March 2nd 2014 Vegetable IPM Updates
 
 
 
Insect Management
Diseases
Weed Science
Question to the IPM Team
Some Videos to Check Out
Pheromone/Sticky Trap Monitoring Network
 
Insect Management:


Leafminer Management on Fall Lettuce

With the weather staying relatively warm so far this fall, insect pressure remains steady. This is indicated in part by our counts taken from in our trap network. Worms remain heavy in most areas, but whitefly flights are beginning to subside except in those areas out east near fall melons. However, as temperatures begin to cool down in the next few weeks, it is important that you not forget about Liriomyza leafminers, particularly as the first produce fields approach harvest. Leafminer numbers have been moderate thus far this season, but we have recently observed higher numbers (adults and larvae) showing up on the older leaves of lettuce here at the Yuma Ag Center. In addition, an increase in adult flies has been observed on yellow sticky traps used for monitoring whiteflies over the past week or so. In most cases, these traps have been located near or adjacent to fall melons, cotton or alfalfa. The 10-day forecast calls for temperatures to be in the 90s for the next week, and leafminer adults should continue to be active. Larval activity could easily cause damage if left uncontrolled in lettuce or baby leaf fields where they are currently present. These larvae can cause significant damage to older, pre-harvest lettuce by feeding and damaging wrapper leaves of head lettuce and romaine. Pupae collecting within the leaf margins can also be considered contaminants. In addition, baby leaf lettuces, spring mixes and spinach are susceptible to larval feeding (mining) on the tender growing leaves. These populations can be effectively controlled with currently available products. Products that are presently being used to control armyworms, loopers and thrips such as, Radiant (5-7 oz/ac), Coragen (5-7 oz/ac), Voliam Xpress (9 oz/ac), and Exirel (15-20 oz/ac) can effectively kill newly emerged larvae in the leaf mines before they cause significant damage. Be sure to include a penetrating adjuvant with these products to enhance translaminar movement of the product and larval control. For more information on leafminer biology and management please go to: Leafminer Management.
Remember, When in Doubt . . . . . “Call John”

Click picture to listen to John’s update video link

To contact John Palumbo go to: jpalumbo@ag.arizona.edu

 

Diseases:


Fusarium Wilt on Lettuce

On October 8th we received our first confirmed sample of Fusarium wilt on lettuce for the 2014-15 production season. Since the first discovery of this disease in Arizona during the 2001-02 growing season, Fusarium wilt has been found yearly in some lettuce fields from mid-October through early January. The initial visual indication of the disease is yellowing of one or more older leaves, followed by leaf wilting and eventually plant death. The external root surface is unaffected; however, a brown to black necrosis of the internal taproot and crown tissue will be apparent. Disease incidence can range from a few plants up to large areas or zones of infected plants within a field. Plants can become infected and display symptoms at any age, ranging from very young plants just after thinning to those ready for harvest. The symptoms of Fusarium wilt resemble two other lettuce disorders, ammonia toxicity and the early stages of lettuce drop. To confirm disease identity, it is necessary to bring plant samples to me at the Yuma Agricultural Center for analysis. Confirmation of disease identity is achieved by isolation and identification of the causal fungus, Fusarium oxysporum, f. sp. lactucae, from symptomatic root tissue. Disease incidence and severity is strongly affected by planting date and the type of lettuce grown. The main determinant of disease severity with respect to planting date is soil temperature. Research data demonstrate that lettuce planted in early September can result in high levels of Fusarium wilt, whereas plantings in the same naturally-infested field started in mid-October or early December sustain moderately low and trace levels of disease, respectively. Of many crisphead and romaine cultivars tested, crisphead cultivars generally are significantly more susceptible to Fusarium wilt than romaine lettuce. There are also significant differences in susceptibility among romaine cultivars. The lettuce Fusarium wilt pathogen can survive in soil for many years, so minimizing the spread of infested soil both within and especially between fields is of paramount importance. Two comprehensive research reports concerning disease development and management of Fusarium wilt of lettuce are available. Please contact me and I will email these reports to you.

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Click picture to listen to Mike's update video link
To contact Mike Matheron go to: matheron@ag.arizona.edu.

 

Weed Science:


Goal “Lift Off”

Codistillation is when a herbicide evaporates or changes from a liquid to a vapor with water. This can occur from soil, water or plant surfaces and can be responsible for substantial loss of some herbicides. When codistillation occurs with Oxyflurofen (GoalTender, Goal 2XL and others), the concern is not herbicide loss but crop injury. Codistillation can occur with several herbicides. It is affected by many factors including temperature, moisture, organic matter, soil pH and other variables. In general, codisillation is greatest when temperatures, moisture and pH are high and organic matter is low. One of the herbicides used in this region that is most affected by codistillation is Eptam (EPTC). A study conducted several years ago in Brawley California found that more than 80% of the Eptam that was applied in irrigation water was lost by codistillation. Most of this was from the soil after it had reached the field. In our trials, we have found that codistillation may help GoalTender and Goal 2XL (oxyfluorfen, also sold as Galligan, Oxi Flo and others) kill weeds but it also can increase crop injury. Goal can move into plants in the vapor phase once it has lifted off and both weed control and crop injury are enhanced. We have seen this when Goal is Chemigated through sprinklers. Goal is primarily a contact type herbicide and moves little in the plant. It works preemergence by killing weeds as they emerge from the soil and contact the herbicide. It is rare for contact type herbicides to work better when overhead water is applied but this seems to be the case with this herbicide. Lift-Off or codistillation of Goal lift off injury seems to be worse this season because of rain. In many cases this potential is exaggerated. Lift-Off of Goal differs from the usual off target drift that can occur with other herbicides. In this case it is movement of the herbicide with water vapor. Moisture must be present and this moisture must evaporate. The vapor normally stays in the field and it is common for a band application to the furrows, for instance, to move across the bed top. Significant movement out of the field normally only occurs with wind. GoalTender is not as volatile as Goal 2XL and is less prone to codistillation but it occurs with both. The picture below is of GoalTender that was applied to the furrows only but it lifted off and covered the entire bed. The crop grew out of this in 2 weeks.

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Click picture to listen to Barry video link
To contact Barry Tickes go to: btickes@ag.arizona.edu.
Area wide Insect Trapping Network Oct 1, 2014


Oct 15, 2014

Results of pheromone and sticky trap catches can be viewed here.

Corn earworm: Corn earworm moths remain very active in the Dome Valley and have significantly increased in the Yuma Valley where numbers on i11 Oct were above 15 moths per night in both areas. Activity also increased in many of the other areas including the Gila Valley and Wellton.

Cabbage looper/Beet armyworm: Beet armyworm moths are active in most areas, but have been particularly heavy in the Yuma Valley and Dome. Cabbage looper moth activity continues to increase across most areas and was heaviest last week in the south Yuma Valley near the River (Co. 14.5 and Levee Rd) and near Texas Hill (47E). Activity has begun to increase in the south Gila Valley.

Whitefly: Adult activity continues to decline in all areas, except out east near 47E. This trap is located adjacent to fall melons which are approaching harvest.

Thrips: Thrips numbers in general are beginning to pick up in most areas, but movement was particularly heavy 2 weeks ago in Dome Valley.

Leafminers: Slight increases were observed last week in most areas. However, a very high number of adults were captured on a trap located at 47E adjacent to melons.

Aphids: Alate (winged) aphids are beginning to show up on traps, particularly in the Yuma Valley. This is not surprising given the north winds over the past week or so. An occasional cabbage aphid was found on the traps, all others were species not important to produce crops.

VIPM_Update_Vol_5_Num_20_002

Click picture to listen to John’s update video link

To contact John Palumbo go to: jpalumbo@ag.arizona.edu

 

Check Out These Videos!
Links:

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.


 
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