Flubendiamide The Arizona produce industry received some good news and some bad news recently. First, the bad news. Earlier this year, the U.S. Environmental Protection Agency (EPA) issued a notice with the intent to cancel flubendiamide products (Belt SC and Vetica) due to potential risks to aquatic invertebrates. Bayer Crop Science was asked to voluntarily cancel all flubendiamide registrations, but subsequently rejected the EPA’s decision and requested a hearing from Agency’s Administrative Law Judge and Environmental Appeals Board (EAB). Unfortunately, the Appeals Board has upheld the earlier EPA decision to cancel the registration of flubendiamide. So, as of today, Belt and Vetica can no longer be sold by Bayer or Nichino in the U.S., but the EAB decided that it would allow distributors and retailers to continue to distribute and sell existing stocks of the two products remaining in inventory. Thus PCAs and growers can continue using remaining product in inventory. This final decision is unfortunate since both Belt and Vetica are important cost-effective alternatives for worm control in produce and melon crops. In fact, among the diamide chemistries, Belt and Vetica were the most commonly used products in fall lettuce. For more information, see this Flubendiamide EAB Decision. 

Sulfoxaflor The good news is that it appears that sulfoxaflor (Sequoia) will soon be registered and available for use on our leafy vegetable and brassica crops this winter. As you may recall the EPA was forced to cancel the sulfoxaflor registration in Nov 2015 based on a court ruling that the agency did not have enough scientific data to sufficiently demonstrate that sulfoxaflor had no unreasonable adverse effects to honey bees. Since then, EPA has been re-evaluating the sulfoxaflor label amended by Dow Agrosciences that now reduces or eliminates exposure to pollinators, and is proposing to unconditionally grant a Section 3 registration for certain crops including leafy vegetables and brassicas. Unfortunately, citrus, cotton and cucurbits are not included in the proposed registration. EPA concluded that sulfoxaflor will likely replace applications of pesticides that are at a higher risk to humans and other non-target organisms (including pollinators) and delaying its registration would delay these benefits. Before the cancellation of sulfoxaflor, Sequoia was used extensively for aphid management on winter and spring produce. For more information on the proposed label go to Proposed Registration of Sulfoxaflor. 

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! 

For those of you interested in the latest developments in Vegetable IPM and/or in need of CEU’s, Yuma County Cooperative Extension has created online workshops that offer CEU and CCA credits for both AZ and CA. Current offerings are the recorded workshops from 2021 Southwest Ag Summit. There’s an ag mechanization session entitled “Advances in Weed Control Technologies”, and several others that readers of this newsletter may be particularly interested in including: “Integrated Pest Management Regulatory Update” “Pesticide-Related Updates: The Latest Presented by the Greatest” “Influence of Irrigation on Insect, Weed, and Disease Management” “Advances in Weed Control Technologies” “Integrated Pest Management in Vegetables”. Please recognize Yuma County Cooperative Extension Agricultural Agent Robert Masson who spearheaded this effort. Click on the image, or here to access Veg IPM workshops online.

Weeds that are outside of fields can still be harmful to crop production. This does not include ditch banks or fallow fields. Non-crop weed control includes weeds around buildings, roadways, equipment yards, fence lines etc. It is different than fallow ground or ditch banks weed control and includes places where crops are not grown. Weeds in non-crop areas can be a source of weed seeds that blow or are carried into places where crops are grown. They can also be a refuge for insects,  diseases and rodents. The reason that these herbicides are registered for non-crop areas is that they are broad spectrum and persistent. Some are registered for use in fields but at much lower rates than for non-crop areas. For instance, Diuron can be used on alfalfa at 1 to 1.5 qts/ac. but is used for non-crop areas at 12 qts/ac.

Herbicide	Weeds Controlled	Activity	Soil Residual	Comments
Bromacil	Broadleaves and grasses	Preemergence	1 to 2 years	The nuclear option Should be incorporated with water. Keep away from roots of desirable vegetation.
Hexazinone	Broadleaves and grasses	Preemergence and Postemergence	1 to 2 years	Keep away from roots of desirable vegetation. Incorporate with water.
Diuron	Broadleaves and grasses	Preemergence and Postemergence	2 years	Incorporate with water but do not leach into roots of desirable vegetation
Prometon	Broadleaves and grasses	Preemergence and Postemergence	1 to 2 years	Must be incorporated with water
Tebuthiuron	Broadleaves and grass. Good on hardwood trees	Preemergence and postemergence	2 years	Incorporate with water. Contact with even on feeder root of desirable vegetation can be lethal
Imazapyr	Broadleaves and grasses	Preemergence and post emergence	1 year	Primarily a postemergence herbicide but is readily absorbed by rootsif incorporated with water
sulfometuron	Broadleaves and grasses	Preemergence and post emergence	1 year	Must incorporate with water
Aminopyralid	Broadleaves	Preemergence	1 year	broadleaves only. Shorter soil residual for weeds but crops can not be planted for 1-2 years

Results of pheromone and sticky trap catches can be viewed here.
Area wide Insect Trapping Network   VegIPM Update, Vol. 12, No. 25, Dec 15, 2021.
 
Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm:            
CEW moth counts remains low across all locations and about average for this time of the season. 
 
Beet armyworm:         
Trap counts decreased in most locations, and well below average for late-November. Most activity in Yuma Valley.
 
Cabbage looper:        
 Cabbage looper trap counts remained low in most and below average for early December.
 
Diamondback moth:    
Adults activity below average for this time of year. Activity in North gila and Dome Valleys associated with nearby cauliflower seed crops. 
 
Whitefly:                       
Adult movement increased last week, particularly in Wellton consistent with melon crops being disked and Cole crops harvest. 
 
Thrips:                         
Thrips adult movement decreased in most locations last week, but increased sharply in Roll. Activity a little below average for mid-November.
 
Aphids:                        
Aphid movement increased in several areas, particularly in Dome Valley. Above average for this time of season. 
 
Leafminers:                  
Adult activity decreased in most areas, about average for this time of season.