Bagrada bug adults generally begin to appear on direct seeded fields and transplants in early September. In fact, trials conducted on untreated broccoli plots at YAC have shown that mid-September has historically been the time that bagrada begin to show up in large numbers; peak abundance of bagrada bug has occurred from late September to early October (see graphs below). However, there has been a trend of lower bagrada bug abundance since 2012, and last fall was the lightest we’ve recorded bagrada populations since we started tracking them in 2010. 
So far this season, we’ve yet to see a bagarada here at YAC, but reports of bagrada in commercial cole crops are beginning to trickle in from PCAs, albeit very few. Similarly reports out of Imperial Valley and Coachella suggest that populations are light there as well. So, what should a PCA expect for this season? Can’t say for sure, but don’t be complacent just because you’re not finding a lot of bagrada adults on your first few fields. It would be wise to assume they will eventually show up in some intensity in some of your acreage, and you should prepare for them accordingly. Here are a few management tips to consider. (1) We’ve learned through research that when monitoring for bagrada bugs at stand establishment PCAs should focus on fresh feeding signs on new plant tissue, and adults later in the day when they are most active. (2) Research in the field has also indicated that direct-seeded and transplanted crops are susceptible to bagrada bug infestations during stand establishment and up to the 6-leaf stage. Furthermore, it doesn’t take a large number of bagrada adults to cause significant stand losses or crop injury. In untreated plots, we have consistently observed significant damage (15-20% blind plants) to direct seeded plants during the first 7 days after emergence (cotyledon to 1-leaf Stage) with only finding an average of 1 bagrada adult / 6 row. (3) Thus, we recommend that if you readily find 5% or more of plants with feeding signs during stand establishment, control should be initiated immediately. This can include chemigation or aerial applications with pyrethroids. Contact insecticides such as pyrethroids, Lannate, and Lorsban should be used once stands are lined out and pipe is pulled. After stands are established and plant size increases up to the 2 leaf stage, or on tagged transplants, consider alternating to dinotefuron (Venom/Scorpion) for protecting plants from bagrada feeding. This neonicotinoid will also provide knockdown of adult whiteflies and nymphs. (4) Also, growers who planted with Nipsit (clothianidin), should begin to closely monitor for fresh feeding damage around 14 days after emergence. More information on bagrada bug management on fall cole crops can be found in: Bagrada Bug Management Tips for the Low Desert.

The drought-related pressures on the Colorado River system that have been impacting the entire basin and region for 23 years have slackened briefly due to the wet winter in 2023 that included a good snowpack in the mountains, better rainfall throughout the basin, and improved flows into the river.  The current water level at Lake Mead on Hoover Dam is 1,068.25 ft. above sea level on 3 January 2024.  That level is 160.75 ft below full pool of 1,229.00 ft. (Figure 1).

 

In mid-December 2023 representatives from each of the seven Colorado River Basin states met in Las Vegas, NV during the annual Colorado River Water Users Association conference.  The focus of current discussions among the basin states is to negotiate a new compromise for the guidelines of use under conditions of water shortage.  These new guidelines will go into place at the end of 2026.  The immediate goal is to draft proposals by March 2024.
 
The negotiations are incentivized by having the opportunity for the post-2026 guidelines being developed by the basin states themselves as opposed to litigation or legislation.  A major concern driving this process among the basin states that basin state representatives should be able to do this better than turning the process over to people and entities that have less direct familiarity with the situation and no real “skin” in the game.  
 
The 1963 decision by the Supreme Court of the United States in of the Arizona v California case directed the federal authority on the management of the Colorado River to the Department of the Interior and the Bureau of Reclamation (BoR).  However, the basin states have the chance to negotiate their future management plans on the Colorado River.  If they fail to do so in the allotted time, the process will be managed by the federal government.  
 
The basic water budget challenge is based on the following basic statistics:
 

• The current water budget on Colorado River allocations is 16.5 million acre-feet (maf)/year.
• Average annual flow on the Colorado River from 1906-2017 was 14.8maf/year.
• The average annual flow between the years 2000 - 2018 has been approximately 12.4maf/year.
• That is 16% lower than the 20^th century average flow.
• It is estimated that 1.5 maf/year is lost due to evaporation and system loss.
• Thus, the 4 maf/year target reduction that has been identified by the BoR is basically the difference between the 16.5 maf/year allocated versus the 12.4 maf/year average flow in the first two decades of this century.

 
Some notable progress is being made for conservation of Colorado River water with agreements among lower basin states and tribes that will conserve more than 1.5maf/year through 2026.  For example, California water agencies have recently agreed to conserve up to 643,000 acre-feet/year through 2025.  The Quechan Indian Tribe has reached an agreement with federal water managers to save up to 39,000 acre-feet/year through 2025.  Arizona has agreed to conserve up to 348.00 acre-feet/year through 2026.  All these temporary agreements are being supported with federal funding.
 
With agriculture responsible for 70% of the diversions on the Colorado River, these negotiations are extremely important for the future of agriculture in this region and our capacity to support high population densities that are now common and rapidly growing.
 
These types of negotiations are certainly challenging in dealing with a limited water supply and a lot of demand.  There are many competing interests involved.  Yet, we are confident that the representatives we have will be able to work this out and come to a set of functional agreements.

Viruses vectored by insects 
 
We are on the final section of virus transmission. Virus transmission by insects is one of the most efficient and economically important transmission in agriculture. When you have insects in your crops, not only you are losing your crops because of feeding/chewing by insects, a lot of insects also act as a vector of plant viruses. 
 
Seven out of 29 orders of insect feeding on living green land plants are vectors of plant viruses. 
Insect transmit viruses in 4 distinct modes: 
 

1. Non persistent transmission: The insects can acquire the virus in a matter if seconds/minutes and they are immediately viruliferous. The virus in retained in the stylet of the insect and are transmitted to the next plant the insect feeds on. The virus is retained in the vector only for few minutes and is lost after insect molting. Most viruses transmitted by aphids are non persistent. So when you see few aphids in your melon field and see cucumber mosaic virus symptoms 1-2 weeks later in your field, don’t be surprised. Aphids are efficient vectors, and since viruses are systemic it takes anywhere from few days to 2-3 weeks for the plants to show symptoms. Thus it is very important to manage insects in the field even if you don’t think the ‘pressure’ is not as high. 

Viruses transmitted in non-persistent manner:
 Papaya ringspot virus 
Zucchini yellow mosaic virus 
Watermelon mosaic virus

1. Semi-persistent transmission: The insects can acquire the virus in minutes/hours and there is no latent (incubation) period in the insect. The virus can stay in the insects foregut for hours and is lost after insect molting. Some species of aphids and whiteflies fall in this category.  Example: Cucurbit yellow stunting disorder virus in melons transmitted by whiteflies. 

1. Persistent circulative: Insects have to feed on virus infected plants for hours/days to acquire the virus and the virus has to incubate for hours/days in the insect. After insect can transmit the virus for weeks. Virus can be present in the vectors hemolymph but there is no multiplication of virus in the insect body. Vectors in this transmission includes: Aphids, leafhopper, whiteflies, treehopper. 

Example: Beet curly top virus transmission by beet leafhopper 
 

1. Persistent propagative:  Insects have to feed on virus infected plants for hours/days to acquire the virus and the virus has to incubate for hours/days in the insect. After insect can transmit the virus throughout its lifespan. The virus can multiply in the vector system and often times the virus particles are also passed on to the insect offspring. Tomato spotted wilt virus is transmitted on persistent propagative manner by 9 different species on thrips. 

 

Save the Date : 2024 Plant Pathology Workshop 
When: August 29^th 8AM-12 PM ( breakfast and Lunch provided by Gowan Company and BASF) 
Where: Yuma Ag Center, 6425 W 8^th Street 
What will covered: Plant Pathology program Updates, past season field trial results (we
have some exciting results to share), Q&A to help better Plant pathology program,
Industry panel discussion for all your industry related questions! See you in few weeks! 

Time flies. February is right around the corner and that means it is farm equipment/ag trade show season. Upcoming regional events include the World Ag Expo, Tulare, CA, February 13-15, the Southwest Ag Summit, Yuma, AZ, February 20-22, and AgroBaja, Mexicali, Mexico, March 7-10.  If you are interested in the latest ag tech and farm machinery, all are outstanding events and well worth attending. For more information, click on the links below.

Fig. 1. Upcoming farm equipment/ag trade show events: World Ag Expo, Tulare,
CA, February 13-15, 2024 theSouthwest Ag Summit, Yuma, AZ, February 20-
22,2024 and AgroBaja, Mexicali, Mexico, March 7-10, 2024.

Before making decisions for weed control it’s imperative to have a proper identification of the plant species. There are two names for plants:
The common name, which is a name that people come up with in a certain region to describe a particular weed and it varies by region and therefore can be confusing. Then we have an exact scientific name for each species that is based in the binomial nomenclature system started by Carl Linnaeus in 1753. This binomial (or two term) system includes the genus and the species, which is used worldwide¹.
 
Some very close species from the same family can be controlled by the same product but occasionally their herbicidal susceptibility varies. Such is the case of Chenopodium murale (goosefoot) and Chenopodium album (lambsquarter) two very close and similar species. A product like Pursuit (Imazethapyr) has good activity on goosefoot but can’t control lambsquarters. With accurate identification in a mixed population, you would be able to determine what strategy to use or select the herbicide that would control both species. 
 
There are about 75 weeds most common in Arizona and are included in the PCA² study guide, but many other species could be introduced to the State and complicate our crop production systems. Two great tools for weed identification are the books “An Illustrated Guide to Arizona Weeds” that lists 172 species, and “Weeds of California and Other Western States” which has at least one photograph of 735 weeds.
Another weed identification tool is the book “Weeds of the West”.
Additionally, there are many phone applications that can be used as identification tools such as “id weeds”, “PlantNet”, “PictureThis”, “iNaturalist”, “Seek”, “PlantSnap” and “LeafSnap”. When we have problems with weed ID we contact the UA herbarium.
Thank you for sending samples for Weed ID to the IPM Team it is always a learning experience.

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.

Leaf miners: Adult activity light in all areas, about average for this time of season