It’s that time of the year to start thinking about management of whitefly nymphs on spring melons. I have had a couple of reports from PCAs that adults are beginning to show up on cantaloupes, and adults can be found on pre-bloom melons here at the Ag Center. As temperatures continue to increase, feeding damage from whitefly nymphs should be a concern on all melon types. Honeydew and sooty mold contamination on fruit of cantaloupes, mixed melons and watermelons can significantly reduce quality and marketability. Although whitefly numbers have been low up to now, PCAs should not be complacent in their monitoring and sampling. With the warmer weather, numbers are likely to increase rapidly in the next few weeks. Our research has shown that to prevent melon yield and quality losses, a foliar insecticide treatment should be applied when a threshold of 2 adult whiteflies per leaf is exceeded. By timing sprays based on the adult threshold, immature populations should just be starting to colonize and applying foliar sprays at this stage in population development has been shown to significantly reduce the chance of yield / quality loss during harvest. This threshold applies for the IGRs (Vetica, Courier, Knack, Oberon), and foliar applied neonicotinoids (Assail, Venom, Scoprion). (For more information, go to these documents on whitefly management, thresholds and insecticide efficacy). Also, be aware of pollinators in or around melon fields. I recommend carefully reading labels to determine the products bee safety before applying any pesticide in melon fields, particularly when bees are foraging. Note: Cucurbit Yellow Stunting Disorder Virus (CYSDV) is not generally known to be yield limiting on spring melons. However, research to date suggests that fall melons may be at greater risk of CYSDV infection when planted in areas where CYSDV symptoms were found on late spring melons. Thus when practical, it is advisable to keep whitefly populations low on spring melons. This will also prevent potential dispersal in to cotton later in June and July.

Bacterial soft rot is caused by several types of bacteria, but primarily subspecies and pathovars of Erwinia caro-tovora and E. chrysanthemi. Other bacterial species that cause soft rot include Pseudomonas cichorii, P. marginalis, and P. viridiflava. They have a wide host range host range and includes genera from nearly all plant families

In lettuce fields, the symptoms are observed close to the harvest time. The tissue, mostly around inside the head of head lettuce softens and becomes mushy or watery. Slimy masses of bacteria and cellular debris frequently ooze out from cracks in the tissues. Decaying tissue, which may be opaque, white,

cream-colored, gray, brown, or black frequently gives off a characteristically putrid odor. The odor is caused by secondary invading bacteria that are growing in the decomposing tissues. The bacteria overwinter in infected fleshy tissues in storage, in the field, garden or greenhouse, in the soil (especially in the rhizosphere around the roots of many plants), and on contaminated tools, equipment, containers, and in certain insects. The bacteria enter primarily through wounds made during planting, cultivating, harvesting, grading, and packing and through freezing injuries, insect and hail wounds, growth cracks, and sunscald. They may also follow other disease-producing organisms. Uninjured tissues may become infected when the humidity approaches 100 percent or when free moisture is present. Rains, poorly drained or waterlogged soils, and warm temperatures favor infection in the field, as does high humidity in storage or transit.

The bacteria multiply rapidly by dividing in half every 20 to 60 minutes under ideal conditions at temperatures between 65° and 95° (18° and 35°C). Minimum temperatures for development is between 35° and 46°F (2° and 6°C); and maximum between 95° and 105°F (35° and 41°C. The bacteria are spread by direct contact, hands, tools and farm machinery, insects, running or splashing water, contaminated, water in washing vats, clothing, and decayed bits of tissue.

Management

Promptly and carefully destroy infected plants. Maintain well aerated field, avoid close planting and overhead irrigation. To minimize post-harvest losses, avoid mechanical injury after harvest, packing and shipping. Do not pack produce when wet. Store and ship produce at temperatures near 4°C (39°F).

Source: IPM.Illinois.edu

Two years ago, Alphabet’s (Google) X-Labs initiated one of their infamous and far reaching “moonshot” projects focused on growing food sustainably on global scale. As you might expect, the project has been, and is kept pretty secret, but the company recently unveiled some details about the project through a company blog article (Grant, 2020) and their newly established website (https://x.company/projects/mineral/). The project is called “Mineral” and according to project lead Elliot Grant, the team has been working “alongside experts in the field – literally and figuratively…developing and testing a range of software and hardware prototypes based on breakthroughs in artificial intelligence, simulation, sensors, robotics and more”.

One of the tools the team has developed is a self-propelled “plant buggy” equipped with multiple cameras, sensors, GPS and other electronic equipment (Fig. 1). According to Mineral’s website, “Over the past few years, the plant buggy has trundled through strawberry fields in California and soybean fields in Illinois, gathering high quality images of each plant and counting and classifying every berry and every bean. To date, the team has analyzed a range of crops like melons, berries, lettuce, oilseeds, oats and barley—from sprout to harvest.” Stated objectives of Mineral’s software are to combine and analyze data collected from the field, soil health information and weather data to 1) predict how different varieties of plants respond to their environments, 2) allow growers to treat individual plants with fertilizers and pesticides to optimize production and reduce inputs and 3) help growers predict the size and yield of their crops.

It is exciting that a cutting-edge tech company like Alphabet is taking on an agricultural project like this. It will be fascinating to see what technical breakthroughs and solutions the company will be able to achieve for all crops, including vegetables.

References
Grant, E. 2020. Mineral: Bringing the era of computational agriculture to life. X Development LLC blog article. Mountain View, CA: X Development LLC. Available at https://blog.x.company/mineral-bringing-the-era-of-computational-agriculture-to-life-427bca6bd56a.

March is traditionally the time when winter annual weeds die and summer annual weeds start growing. Weed management would be much easier if this transition was clear cut. Like everything else, many factors can complicate this. Especially here in the low desert with mild winters and summer irrigation. Some summer annual weeds have survived all winter and some winter annual weeds will grow all summer. Sprangletop and sandbur are classified as summer annuals but they have survived all winter in a dormant state and will regrow from established crowns as it continues to warm up. Not all survive the winter and some new plants will come from seed this summer. Those coming from seed can be controlled with preemergence herbicides but those coming from crowns can not be. Other weeds that survive year round that are not normally classified as perennials are clovers, mallows and thistles. Many of these have become very widespread and difficult to control. White sweet clover and both green and Mexican sprangletop have become more widespread every year.

Results of pheromone and sticky trap catches can be viewed here.
 
Corn earworm::            
CEW moth counts continuing to increase in areas, and about average for late-September
 
Beet armyworm:         
Trap counts increased in most locations, bet well below average for mid- September.
 
Cabbage looper:          
Cabbage looper activity slowly increasing, particularly in  Dome Valley and Wellton. About average for this time of season.
 
Diamondback moth:     
DBM moths starting to become active in a few areas (Dome and Wellton); below average for this time of the year.
 
Whitefly:                      
Adult movement increased in the past week, but below average for this time of year. 
 
Thrips:                          
Thrips adults increased markedly in many locations (Tacna, Dome, Yuma Valley), and higher than previous years.
 
Aphids:                        
Aphid movement is absent and consistent with what we typically see during September. 
 
Leafminers:                   
Adult activity up in a few locations (Yuma Valley), below average for September.