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University of Arizona
March 2nd 2014 Vegetable IPM Updates
Insect Management
Weed Science
Some Videos to Check Out
Insect Management:

Insect Pests Important at Stand Establishment in Fall Crops

It’s that time of the year again. Desert growers have begun planting fall melon crops, transplanting cabbage and will be direct seeding leafy vegetables in just a few weeks. Soon to follow is a number of important insect pest issues. As crops begin to emerge, PCAs will begin to encounter insects that have 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 all have chewing mouthparts and most are capable of consuming large amounts of leaf tissue in a short time. Seedling crops at the cotyledon stage are most susceptible to these pests, where feeding by large numbers can devour much of the cotyledons or outright kill the small plants. If left uncontrolled, larger seedling plants (2-4 leaf stage) can sustain significant feeding damage on the terminal growing points or newly emerged leaves. Not only can this feeding stunt plant growth, but it can result in lack of uniformity and maturity at harvest. Host sources of flea beetle, cricket and "woolly worm" infestations include numerous summer crops (e.g., sudan grass, cotton and alfalfa) and a large host of weeds (e.g., purslane). Experience indicates that melon fields planted adjacent to these crops/weedy areas are at a high risk from these seedling pest, and particularly flea beetles. As summer crops are harvested or terminated during the next several weeks, these seedling pests typically move to the next available host crop; lettuce, cole crops and melons. Fortunately, there are many registered insecticide alternatives available that can be applied via sprinkler chemigation (i.e., pyrethroids) or foliar sprays (i.e., Lannate, neonicotinoids) that can cost-effectively minimize their abundance and damage to emerging produce and melon crops. For more information on insect pests of leafy vegetables and melons at stand establishment go to the document Pests at Stand Establishment 2014.
Pale Striped Flea Beetle
Remember: "When in Doubt...Scout"

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Additional Comments on Summer Preplant Soil Flooding as a Management Tool for Sclerotinia Lettuce Drop

As stated last time, research studies revealed that a 3-week period of field flooding during the hot summer months of July and August proved to be an effective cultural means of controlling Sclerotinia lettuce drop in future lettuce plantings, as this procedure destroyed virtually all sclerotia of Sclerotinia minor and S. sclerotiorum in soil. During 2011 and 2012, over 4,200 and 3,600 acres, respectively, were subjected to preplant soil flooding in the Yuma Valley. However, some negative effects of this practice have been noted in certain situations. One concern is the rising of the ground water table, particularly in areas already affected by high ground water. Also, in certain areas in the Yuma Valley, damage to the open drainage system has occurred as a result of erosion of the sides of earthen drains. These concerns have led to the initiation of additional field research at the Yuma Agricultural Center to examine and possibly refine the method of water delivery and the duration of soil wetness required to destroy sclerotia of Sclerotinia minor and S. sclerotiorum. The goal of this research is to achieve destruction of the Sclerotinia lettuce pathogens in soil with the least amount of water. A research trial currently in progress will tell us if this is possible. Although summer soil flooding may not be appropriate for all ground planted to lettuce, this cultural practice can be an effective component of an integrated management program for lettuce drop.
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Weed Science:

Band Application of Herbicides

Band applications of herbicides are less common than band applications of insecticides because weeds need to be controlled in the entire field and not just in or on the plant area. Banding herbicides in row crops is not uncommon, however, and has several advantages. The primary advantages are reduced cost and herbicide carryover in the soil. Banding over the crop row is often combined with cultivation. Cultivation is cost effective with immediate gratification. Determining the rate of application when making band applications is sometimes misunderstood and or abused. The application rate should be the same for both band and broadcast applications but the treated acreage will differ depending on the band width. If, for instance, a 50% band is applied on a 10 acre field, 5 acres will be treated. The amount of both water and herbicide should be calculated for 5 acres. This is fairly straight forward but often misunderstood. The key is to calculate the amount you put in the tank based on the actual area that will receive the chemical, not the total area in the field. It can be tempting, when the herbicide is inexpensive and easily accounted for, to apply higher than labeled rates to increase weed control. A good example of this is the use of glyphosate on roundup ready cotton. Although crop safety is well known with this herbicide, there are some instances where other herbicides can cause injury at higher than labeled rates. More important, however, is that this practice increases the possibility of herbicide resistance. Selection pressure for resistant biotypes increases with higher than labeled rates. The rapid increase in the number of glyphosate resistant weeds in the Midwest has been alarming. One of the primary reasons for this has been the progressive increase in application rates to control tough weeds. Increasing rates is a short term solution that can cause long term problems.
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Real IPM

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Check Out These Videos!

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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