Jan 24, 2024Avoid Seed Corn Maggots in Spring Melons (2024)To contact John Palumbo go to: jpalumbo@ag.Arizona.edu
With melon season on full bloom, you will also start seeing diseases on melons. Cucurbit yellow stunting disorder is more of a problem on fall melons but they can also occur in summer melons. Cucurbit yellow stunting disorder is a cucurbit disease caused by a plant virus named Cucurbit yellow stunting disorder virus (CYSDV; genus Crinivirus, family Closteroviridae). This virus was first detected in southern California and Arizona in 2006 and infects cantaloupe and honeydew melon, watermelon, and various types of squash. CYSDV is transmittedexclusively by the whitefly, Bemisia tabaci. Symptoms always start from the oldest leave which is a diagnostic feature of the virus.
All biotypes of B. tabaci known to exist in North America can transmit the virus efficiently, including biotypes A, B and Q. Whitefly transmission is responsible for virus spread over short distances (e.g., within and between fields). However, with high winds whiteflies can move long distances and transport the virus. The virus can stay infectious within whiteflies for up to 9 days. As virus infection is systemic (meaning they have to be circulated inside the plant system to show symptoms) it can take 3 to 4 weeks for disease symptoms to develop following infection. This gives a window for infected symptomless plants can be unknowingly transported and can lead to epidemics. The virus is not transmitted mechanically (by touch, mechanical damage, cuts etc) or via seed. However, the virus can be efficiently transmitted even if there is low whitefly pressure in the field.
The best management approach is to monitor the whitefly population and be proactive with insecticides application. Rotate insecticides with different modes of action Group numbers to minimize development of insecticide resistance. Practice good weed management in and around fields to the extent feasible. Remove and destroy old crops/volunteers, enforce regional cucurbit -free period to eliminate the virus from the cropping system.
Sweet Shield and Novira varieties seem to do well in Yuma area.
A couple years ago, we conducted evaluations of various “new” technologies for cultivating weeds in cotton as compared to conventional methods. The new technologies included 1) a camera-guided side-shift hitch and 2) finger weeders, an in-row weeding tool (Fig. 1). Camera-guidance of the maneuverable hitch allows cultivating tools to be positioned close to the seed row. In the study, the uncultivated band was 3.5" for the camera-guided system, and 6” for the conventional cultivator. The aim of evaluating these technologies was to determine their efficacy in controlling herbicide resistant weeds. Trials conducted over 3 years showed that use of camera-guidance improved weed control by more than 30% and finger weeders removed about 45% of the in-row weeds. Overall weed control using the two technologies together was roughly > 90% for broadleaf weeds and about 85% for all weeds species.
Studies conducted by Texas A&M over two years showed similar results (Dotray et. al, 2021).
It is logical to think that similar type results would be realized in vegetable crops such as broccoli and cauliflower, plants that also have fairly long plant stems at the seedling stage of growth. A better than 40% reduction of in-row weeds would significantly lower hand weeding requirements. If you are interested in trying these technologies in vegetable or other crops on your farm, please contact me. We still have the equipment and I’d be happy to work with you.
A presentation given on the trial results and videos of the equipment used operating can be found by clicking here or on image below.
Dotray, P.A., Keeling, J.W., & Russell, K.R. 2021. Precision cultivation with finger weeder systems. Project No. 20-190 Final Report. Cary, N.C: Cotton Inc.
Project partially funded and supported by Arizona Cotton Growers Association, Cotton Inc., KULT-Kress, LLC and Keithly-Williams Fabrication. We thank them for their support.
Fig. 1. Technologies for precision cultivation and in-row weeding used in
efficacy trials included a a) a camera-guided side-shift hitch attached to a
cultivator and b) in-row weeding tools (finger weeders).
Fig. 2. Click on image above to watch presentation on precision cultivation and
in-row weeding technologies.
The following is the FIRST WEED SCIENCE ARTICLE OF THIS NEWSLETTER published January 13, 2010 by our friend Barry Tickes.
The selective grass herbicides are good rescue type treatments in vegetables for grasses that have gotten through Pefar, Kerb and Balan. These include Poast (sethoxydim), Select (clethodim) and Fusilade (fluazifop) and the generics of these products. These herbicides are all slow and even slower as temperature and day length drop. If you don't like weeds, you can have the satisfaction of watching them suffer for a long time. Treated grasses should stop growing immediately and will slowly turn yellow, red and gradually disappear as the crop grows. This will likely take 2 to 3 weeks. Poast is the slowest and Select is the fastest. All of these herbicides require the addition of a crop oil concentrate except for Select Max which you can use with either a crop oil concentrate or non-ionic surfactant. Some reports indicate that ammonium sulfate will help in cold weather. If you have used one of these products and don't see adequate control within 3 or 4 weeks, please contact us and we'll look at it with you.
As Barry promised in his 2010 article he will be looking at some field trials with me today!