Spring melon crops are rapidly growing, and so are insect pest populations.  Whitefly adults are becoming noticeable, and PCAs should be diligent in their monitoring and sampling. Overall, whitely populations are quietly becoming abundant on the spring melons of all sizes. Adults can easily be found on recently planted melons located at the Yuma Ag Center, and reports from local PCAs suggest that adult populations are beginning to show up on older plantings. As temperatures increase and crops/weeds mature, avoidance of excessive feeding from whitefly nymphs should be a primary concern on all melon types. Honeydew and sooty mold contamination cantaloupes, mixed melons and watermelons can significantly reduce quality and marketability.  Our research has shown that to prevent fruit yield and quality losses on spring melons, a foliar insecticide treatment should be applied on threshold; that is, when leaves have greater than 2 adult whiteflies per leaf, when averaged across an entire melon field. At this level of adult abundance, immature populations should just be starting to colonize, and timing sprays based on the adult threshold has been shown to significantly reduce the chance of yield / quality loss during spring harvests.  This threshold applies for the use of recommended IGRs (Courier, Knack, Cormoran, and Oberon), foliar applied neonicotinoids (Assail, Venom, Scorpion), diamides, (Exirel and Minecto Pro) and the new feeding disruptors (PQZ and Sefina).  On watermelons, Sivanto is also available. For more information on whitefly management and available insecticides, go to these documents on IPM and Whitefly Management and    Whitefly Control Options. Also, be aware of honeybees and other pollinators in or around melon fields. If bees are present, be sure to carefully read labels and determine bee safety of a product before making an application in a melon field.  If applications are necessary during bloom, only apply a product that is considered bee safe (e.g., PQZ, Sefina, Sivanto, Assail). We also recommend that insecticides only be applied when honeybees are not actively working in the field (e.g. 10:00 pm – 3: 00 am).

Name the insect pest below:

Image courtesy of Mike Arbogast

CONGRATULATIONS!

Jose Martinez correctly ID'd the insect in the picture as painter lady caterpillar.
Thank you all for your participation.

Root systems provide the foundation for plant development.  At the time of seeding and plant establishment, it is important to monitor and evaluate the newly developing root systems; subsequent plant growth depends on them.  
 
Roots are responsible for all water and nutrient uptake by the plant, and they provide the physical anchoring and support of the plant structure.  Each plant and crop species has its own “personality” and growth habits, including root systems.  Accordingly, root systems have unique characteristics among plants species.  
 
Young plant roots, particularly at the time of germination and stand establishment, are generally the most sensitive plant part to soil and water salinity.  In fact, seedling plant sensitivity to salinity can often be measured by approximately ½ of the tabulated salinity tolerance guidelines.  
 
In general plant root systems constitute 30-50% of the total plant dry matter.  When post-harvest plant residues are incorporated into the soil, the root systems provide a significant contribution to that plant material and final carbon (C) contributions to the soil, which is an important factor contributing to soil health.
 
The first thing a seed develops in the germination process is a primary root that grows downward into the soil.  We often refer to this as the “stinger” root that extends from a germinating seed.  New cells are formed at the tip of the primary root as it extends downward into the soil forming a “thimble-shaped” cluster of cells called a root cap (Figure 1).  
 
The root cap serves as a type of shield that helps the root penetrate the soil matrix and protect the developing root tissue.  As the root grows downward into the soil the root cap cells are sloughed off creating a slimy surface that helps lubricate the root as it extends deeper into the soil.
 
The growing point (apical meristem) for the developing root is just behind the root cap and this is the zone of new cell formation that facilitates root growth and replaces the cells that are sloughed off as the root grows through the soil.  The new cells elongate and serve to extend the roots into the soil (Figure 1).
 
The most active parts of the plant root system for mineral nutrient and water uptake are in the tiny root hairs that are formed in zone behind the apical meristem.  Root hairs are only formed in the relatively new and freshly developed root tissue.  The root hairs are extremely small, tender, and physiologically active.  Healthy fresh young roots and root hairs should be clean and white.
 
Root hairs are often referred to as “feeder roots” due to their high-level of activity in securing water and nutrients from the soil for the growing plant.  In the process of transplanting, it is important to protect the feeder roots as much as possible and promote their health to ensure rapid adaptation to the new soil environment.
 
Young plants have the capacity to develop basic aboveground tissue to perform sufficient photosynthesis for establishment and growth due to the plant’s ability to take up mineral nutrients and water from the soil from the root system.  Sometimes it can appear that plants are not growing rapidly while the young crop is investing energy and resources into root system development, which is the foundation for the subsequent plant growth and development.
 
The depth of the roots will vary according to the soil physical conditions and effective soil depth, soil fertility and salinity management, plant-available water, and of course the natural rooting characteristics of the plant.
 
In general, there are two basic types of plant root systems.  Broadleaf plants (dicotyledonous) and coniferous plants (gymnosperms) commonly have a taproot system the extends downward through the soil developing root branches from the primary root stem (Figure 2).
 
Grass plants and their relatives (monocotyledonous plants) produce fibrous root systems that branch extensively and radiate out into the soil from the plant base (Figure 2).
 
In general, taproots tend to be deeper with extensive branching from the primary root, develop woody tissue on older roots, and are generally long-lived.  In contrast, fibrous roots tend to be smaller, short-lived, with less branching.  
 
As roots age, they become more fully developed in conducting nutrients and water to the growing points of the plant, both above and belowground.  In all cases, the young and freshly developed root hairs (feeder roots) are the primary zone of water and mineral nutrient uptake.
 
As root systems age, the older roots will die, and new root tissue is formed.  As dead roots are sloughed off, the discarded tissue is attacked by naturally occurring, beneficial soil organisms (bacteria, fungi, protozoa, and worms) the release mineral nutrients and produce soil organic matter.  Turnover of root tissue is an extremely important aspect of plant contributions to soil carbon (C), organic matter, and general soil health.
 
We do not see the plant root systems and we cannot watch root hair development.  But it is good to be conscious of root system development since all mineral nutrient, water uptake, and structural support is provided through the roots.  
 
It is necessary to sacrifice a few plants occasionally and evaluate root system health and development.  Accordingly, it is good to review and understand normal root structure and function as we work to manage crop plants for optimum growth, development, and yield.

Figure 1.  Basic root tip anatomy.


Figure 2.  Examples of taproot and fibrous root systems.

Bacterial leaf spot is caused by the bacterium, Pseudomonas syringae pv. Aptata. Hosts of the pathogen include Table beet, Sugar beet, Spinach, Swiss chard, Snap bean, Dry bean, Cantaloupe, Pumpkin, Squash, Lettuce, and Pepper.
 
Significance
Bacterial leaf spot is most commonly found affecting table beet at early stages of growth. This may be because younger plants are more susceptible. It may also be related to the prevalence of cool, wet conditions at the beginning of the cropping season. These conditions are most conducive to infection and disease development. The disease may affect green leaf area in developing seedlings and in severe cases can lead to plant death. Diseased leaves will lead to weakened seedlings which may affect transplant success. Bacterial leaf spot does not directly affect root quality.

Figure 1. Bacterial leaf spot caused by Pseudomonas syringae pv. aptata of
table beet: (left) Small focus of the disease, and (right) 2-6 true leaf stage of
plants affected by the epidemic.

Symptoms
Bacterial leaf spot symptoms are irregular in shape and black to brown in color. The spots may occur across the leaf surface but have a tendency to occur on the leaf edges. Lesions are water-soaked not often accompanied by chlorosis (yellowing). Lesions may initially be small (up to ¼ inch in diameter) but if conditions are conducive may rapidly expand and coalesce but do not cross major veins. The leaf is usually puckered and deformed around the lesions, especially if they occur on the margins (Fig. 2). When the disease is severe, the affected the tissue may also tear giving the appearance of abiotic damage such as hail.

Figure 2. Symptoms of bacterial leaf spot on table beet (cv. Merlin). Note the
black color of the lesions and puckering and deformation of the leaves around
the symptoms.

Bacterial leaf spot symptoms may be confused with other fungal foliar diseases (e.g. Cercospora and Phoma leaf spots; see complementary fact sheets for these diseases) and insect damage (e.g. thrips). Bacterial leaf spot lesions do not have black pin-head, fungal structures across the lesions as found in Cercospora leaf spot. Phoma leaf spot lesions also have small, black structures within the lesions but found in rings and usually accompanied by an ooze of spores.

Disease Cycle

Figure 3. Schematic diagram of the potential sources of Pseudomonas syringae
pv. aptata inoculum which may contribute to Bacterial leaf spot epidemics in
table beet.

P. syringae pv. aptata may be introduced to the table beet crop through several ways (Fig. 3). P. syringae pv. aptata is seedborne and infested seed is a common means of pathogen introduction into table beet fields. The pathogen can also be present in the infested crop residues from the previous season as well as the alternative hosts. Alternative crop hosts include typical Chenopods (e.g. spinach, sugar beet, and Swiss chard) but also other non-related species including beans, cucurbits, and lettuce. Cool temperatures between 45-60°F and wet conditions typical of those that occur in early spring in upstate New York are conducive for pathogen infection and disease development. These conditions are similar to those that predispose table beet also to Phoma leaf spot. The pathogen can spread within the field through infested seed and irrigation water.
Disease Management
One of the most critical factors to achieve management of bacterial leaf spot is the use of certified seeds (Fig. 4). Other factors that will also contribute to reducing the initial inoculum and hence risk of disease include: (i) tillage to bury plant residues to promote breakdown, (ii) rotation between host crop species of at least three years; and (iii) drip or furrow irrigation to avoid dispersal of the pathogen through water splash. Currently, little is known of differences in cultivar susceptibility to bacterial leaf spot. Anectodal reports have described severe epidemics in cvs. Merlin, Boro, and Pablo.

Figure 4. Complementary practices towards the management of Bacterial leaf
spot of table beet.

In-season control. If bacterial leaf spot is severe, applications of copper-based products should be considered to prevent disease spread. There are a range of conventional and OMRI-listed copper-based products available, including: Cueva (copper octanoate; FRAC M1), Badge X2 (copper oxychloride + copper hydroxide; FRAC M1), and Kocide 3000-O (copper hydroxide; FRAC M1). Remember to check the label for rates, re-entry intervals, and pre-harvest intervals applicable to your state and crop. Avoid applying copper-based products on transplants before hardening off, and in high temperatures due to the risk of phytotoxicity.
 
Source: 
 https://www.vegetables.cornell.edu/pest-management/disease-factsheets/bacterial-leaf-spot-of-table-beet/

Interested in staying up to date on the latest robotic ag technologies? FIRA USA and a number of other entities are organizing a 3-day forum focused on autonomous farming and agricultural robotics solutions. The event will be held October 22-24 in Woodland/Sacramento, CA. The program includes top-level keynote speakers, breakout sessions, a trade show and field demos. Over 35 robots will be demoed and/or on display including 8 machines designed for weeding vegetable crops. Some of the latest technologies for in-row weeding will be featured including lasers (2 companies) and high precision spot spraying (3 companies). If you are interested in ag tech, FIRA 2024 promises to be a quality event and one well worth attending. For more information, visit https://fira-usa.com/.

Fig. 1. Robotic technologies on display and being demoed in the field at
FIRA USA 2024. The event will be held October 22-24 in Woodland/Sacramento,
CA. (Photo credits: FIRA USA).

We are receiving some summer grass samples for identification. As you know the seedlings look very similar. 
PCAs have mentioned, and we can corroborate that some species respond differently to herbicides. As an example, we have seen that Sprangletop (Leptochloa filiformis) is not controlled with selective postemergent herbicides like Fusilade or Poast.  We have seen only good results with a high rate of clethodim (Select), and the generics off the same active ingredient. Sandbur is also tolerant to these herbicides.
These two weeds frequently come back from crowns surviving the winter which makes spring preemergence herbicides applied ineffective.
The following are common species of summer annual grass here:
 

 
 Check out the Summer Annual Grass ID publication which contains pictures and descriptive characteristics of each of these species.

I am delighted to embark on my first produce season here in Yuma, AZ. I am looking forward to becoming acquainted with the growing region this fall as we begin identifying tools that can enhance our pest management strategies, specifically focusing on organic solutions for managing insect pests in the Desert Southwest. It is also important for me to gain a deeper understanding of the challenges and issues you are facing in the field. We are eager to evaluate both current and new biopesticides in our upcoming trials and look forward to engaging with potential collaborators. 

Here is a list of our fall 2024 trials: 

1- Evaluation of selected bioinsecticides against Lepidopteran pests in Brassicas 

2- Evaluation of selected bioinsecticides against whiteflies in Brassicas 

3- Alternative bioinsecticides for thrips management in lettuce 

4- Assessing the effectiveness of beneficial insects (T. brassicae, T. pretiosum, and green lacewings) release for diamondback moth control in Brassicas 

I hope everyone’s season gets off to a fantastic start. Please contact me or Macey if you have specific pest issues, biopesticides, or other organic IPM practices you would like us to evaluate. Your expertise is truly invaluable to us! 

Contact Information: 

• Wilfrid Calvin
Assistant Professor & Extension Specialist
Cell: (979) 709-9762
Office: (928) 782-5861
e-mail: wilfridcalvin@arizona.edu 
 

• Macey Keith
Assistant in Extension
Cell: (928) 580-5785
e-mail: maceyw@catmail.arizona.edu 

Area wide Insect Trapping Network   VegIPM Update, Vol. 15, No. 21, Oct 16, 2024

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

Corn earworm: CEW moth counts increased in most traps; about average for early October.

Beet armyworm: Trap counts increased in most areas last week, and about average for early October.

Cabbage looper: Cabbage looper trap counts still most locations, below average for this time of the season.

Diamondback moth: Adult activity increasing, particularly in the Yuma and Dome Valleys.  Above average for this time of season.

Whitefly: Adult movement increasing Tacna, Dome Valley and Yuma Valley; overall about average for early October.

Thrips: Thrips adult movement picking up in all areas, overall activity above average.

Aphids: Winged aphids beginning to show up the north Yuma and Gila Valleys; about average for early October.