In the last two issues of this UA Vegetable IPM Newsletter, I have presented a melon (Cucumis melo ‘reticulatus’ L.) crop phenology model (Figure 1; Silvertooth, 2025a) based on actual heat unit accumulations (86/55 ºF thresholds). This model can be useful in predicting and tracking crop development and identifying important stages of crop growth and development (crop phenology).
Referring to the data from AZMET for several locations in the Yuma area, the HU accumulations from 1 January 2025 for a set of four possible 2025 planting dates are listed in Table 1. The HU accumulations from 1 January 2025 to 28 April 2025 for these sites are listed in Table 2.
The HU accumulations after planting (HUAP) for these four possible planting dates for three Yuma area locations to 28 April 2025 are shown in Table 3. The HUAP values in Table 3 are simply the difference between the values in Tables 1 and 2.
An example for the Yuma Valley, 15 January 2025 planting date is: HU from 1 January to 28 April 1096 - 73 HU accumulated at planting on 15 January = 1023 HUAP for this case.
The information in Table 3 can help serve as a reference to check for melon crop
development in the field against this phenological model in Figure 1. In the most edition of this newsletter (Silvertooth, 2025b) the projected stages of growth were presented based on this phenological model and current HU accumulations.
Based on this phenology model and current HU accumulations for this season we should be able to make some projections on the current stage of growth, which we can go to the field and check. For example, for melon fields in the lower Colorado River Valley at this time, we can expect to find fields planted and watered up in mid-January to have crown set melons maturing and approaching harvest conditions. These fields could have crown fruit ready for harvesting in about three weeks, based on these projections and normal HU accumulation patterns for this time of year. For fields planted and wet dates near the first of March, these fields should have small crown set melons approaching golf ball size.
Table 1. Heat unit accumulations (86/55 ºF thresholds) after 1 January 2025 on four
possible 2025 planting dates utilizing Arizona Meteorological Network (AZMET) data for
each representative site.
Yuma Valley: https://azmet.arizona.edu/application-areas/heat-units/station-level-summaries/az02
Yuma North Gila: https://azmet.arizona.edu/application-areas/heat-units/station-level-summaries/az14
Roll: https://azmet.arizona.edu/application-areas/heat-units/station-level-summaries/az24
Table 2. Heat unit accumulations (86/55 ºF thresholds) after 1 January 2025 to 14
April 2025 utilizing Arizona Meteorological Network (AZMET) data for each
representative site.
Table 3. Heat unit accumulations (86/55 ºF thresholds) after planting (HUAP) from four
possible 2025 planting dates and three sites in the Yuma area on 30 April 2025 utilizing
Arizona Meteorological Network (AZMET) data for each representative site. Each value
is rounded to the next whole number. Note: the values in Table 3 are determined by
taking the difference between the HUs for each representative site and four planting
dates in Tables 1 and 2.
Figure 1. Melon (cantaloupe) phenological development model expressed in Heat Units
Accumulated After Planting (HUAP, 86/55 oF).
Founded in 2016, FarmWise has been at the forefront of AI based weeding technologies for nearly a decade. Over this time, the company has raised over $65 million in capital. In 2023, the company launched their flagship machine, Vulcan - a 21’ wide automated in-row smart cultivator for vegetable crops, priced at $645,000 (Fig. 1). In a surprising announcement just two weeks ago, FarmWise stated that the company was going through a business restructuring and will cease operations in the coming weeks. The bottom line for the decision was that despite having a field-tested automated weeding machine that reduces hand weeding labor costs, the company has not been able to reach profitability with the resources on hand. Moving forward, the company says that they are actively pursuing strategic opportunities including acquisition, partnerships and technology transfer to ensure the Vulcan technology lives on. During the transition, their number one priority is supporting current customers.
For insightful details on the need for restructuring and FarmWise’s plans going forward, you can refer to articles from The Packer and AgFunderNews.
Fig. 1. FarmWise’s automated in-row smart cultivator, the Vulcan, operating in Salinas,
CA. (Photo credit: FarmWise, Santa Clara, CA)
Reference to a product or company is for specific information only and does not endorse or recommend that product or company to the exclusion of others that may be suitable
In the August 21, 2024 update we mentioned our plans to do a demonstrative trial at the Yuma agricultural center. This experiment was established on 10/2 and planted on 10/14. Sprinklers started on10/15. A stand evaluation was done on 10/28 and Phytotoxicity and Goosefoot and Lambs quarter weed control evaluated yesterday. The treatments suggested by some of the people in the industry, where:
Treflan (trifluralin) Applied at 1.5pt/A pre-emergent on the flat ground incorporated mechanically by disking approximately at 4” depth, then make the beds and plant the crop to germinate with sprinkler irrigation. The same method was utilized for Prowl herbicide at the rate of 1 pint product per acre. Also Prowl non-incorporated was included, Devrinol2XL at 1 pt/A, Prefar at 6qt/A as well as a high rate of Goal (oxifuorfen)preemergence to evaluate and document phytotoxicity levels.
As mentioned, we have collected weed control data, which we plan to include in future updates.
Would you like to see how this treatments look? Some of the observations, even though expected are very interesting, such as the fact that 16 floz of Goal Tender preemergence didn’t allow goosefoot germination but similarly broccoli didn’t emerge.
Come to the NW corner of the Ag Center (you can’t miss it) and look at the plots and see the difference between Prowl mechanically incorporated and non-incorporated, compare it with Prefar and Devrinol. We put some very clear signs as you can see in the picture above. The experimental plots are 14x60ft so they are large enough to illustrate what would happen in a farm.
We thank you for your suggestions ...please come and let us know what you think!
Aphids are considered the most difficult to control insect pests in organic vegetables due to the lack of effective bioinsecticides as well as their ability to hide within plant structures. For instance, lettuce aphids normally hide in the head or heart of lettuce, making them difficult to reach by insecticide treatment or natural enemies. It is important to adopt other methods, such as nitrogen and water management, for additional aphid suppression.
As sap-sucking insects, aphids depend on the nutritional content of the sap ingested from the plant hosts for proper growth and development. Nitrogen availability is one of the most important factors in the development of aphid populations. Thus, limiting your nitrogen application to the optimum amount required for your crops is good practice for maintaining your aphid population below damaging level. Additionally, the use of slow-release (minimizing the risk of nutrient deficiency or excess) nitrogen fertilizer can be beneficial for aphid control. On the other hand, excess of nitrogen will make your crops a superfood for aphids. This accelerates the growth, development, and reproduction of the pests, reduces their generation time, and results in an increase in the number of generations and density during the cropping season. Excess of nitrogen particularly affects aphids on host crops such as lettuce, wheat, and sorghum. In some situations, high nitrogen levels in plant tissue can decrease resistance and increase susceptibility to aphids’ attacks. Applying the optimum amount of nitrogen fertilizer can tremendously help to manage aphids. In addition to pest management, effective fertilizer usage can also result in economic and environmental benefits.
Selected References:
1- Altieri, M. A., C. I. Nicholls, and M. A. Fritz. Manage insects on your farm: a guide to ecology strategies. SARE. https://www.sare.org/resources/manage-insects-on-your-farm/
2- Aqueel, M. A., and S. R. Leather. 2011. Effect of nitrogen fertilizer on the growth and survival of Rhopalosiphum padi (L.) and Sitobion avenae (F.) (Homoptera: Aphididae) on different wheat cultivars. Crop Protection. 30:216-221.
3- Bal, R., M. Groshok, and Y. Jama. 2024. Effects of nitrogen and potassium-based fertilizers on green peach aphid and abundance and arugula condition and growth. The Scientist. 6:1. https://journals.mcmaster.ca/iScientist/article/view/2931
4- Sinha, R., B. Singh, P. K. Rai, A. Kumar, S. Jamwal, and B. K. Sinha. 2018. Soil fertility management and its impact on mustard aphid, Lipaphis erysimi (Kaltenbach) (Hemiptera: Aphididae). Cogent Food & Agriculture. 4: 145094.
5- Xia, C., W. Xue, Z. Li, J. Shi, G. Yu, and Y. Zhang. 2023. Presenting the Secrets: exploring endogenous defense mechanisms in chrysanthemums against aphids. Horticulturae. 9: 937. https://doi.org/10.3390/horticulturae9080937
Supplying the optimum amount of water to your crop is also very important for effective pest control. Water availability around plant roots increases nitrogen absorption. Additionally, with high water availability, there is an increase in phloem pressure, making food more accessible to sap-sucking insect pests. Supplying the required amount of water using appropriate irrigation methods and irrigation scheduling can be beneficial for pest management. Although these practices will not completely prevent infestation of aphids, they can surely play a role in reducing the density of aphid populations on your crops.Organic farming faces two major challenges: weeds, which remain the number one concern, and insect pressures that can severely affect crop quality and yields. Effective strategies for managing weeds and insects are critical, especially as organic production expands. Traditionally, these tasks have been labor-intensive and time-consuming, creating a strong need for innovative solutions that can improve efficiency while maintaining crop standards. With the current momentum for increased AI integration into agriculture supported by both industry and Washington D.C., novel technologies AICropCAM present exciting opportunities for leafy green growers. These high-tech platforms could offer early-stage detection of weeds and insects, helping growers respond more quickly and precisely. Such innovations have the potential to save significant time and labor, particularly across large acreages, while improving overall crop management decisions.
What is AICropCAM, and How Does it Work?
AICropCAM (Figs. 1, 2, & 3) is an advanced edge image processing platform designed to extract plant and canopy features directly from field crops. Its structure includes three key layers:
One of AICropCAM’s biggest advantages is its ability to perform deep learning-based image processing directly in the field. This means it can detect subtle signs of weed emergence or insect damage in real-time, capturing critical information that traditional imaging or simple sensors often miss. Edge computing also significantly reduces the need for high-bandwidth data transmission, a major limitation in rural agricultural areas.
Looking Ahead
Incorporating AICropCAM into leafy green production systems could help growers proactively manage weeds and insect pressures, optimize resource use, reduce chemical interventions (especially important in organic systems), and save time and labor. These technologies offer a glimpse into the future of precision agriculture, where early detection and informed decision-making can significantly boost sustainability and profitability.
Figure 1 (left): AICropCAM-insect detection, Figure 2 (middle): AICropCAM-weed
detection, Figure 3 (right): AICropCAM-installed in the field.
