This study was conducted at the Yuma Valley Agricultural Center. The soil was a silty clay loam (7-56-37 sand-silt-clay, pH 7.2, O.M. 0.7%). Spinach ‘Revere’ was seeded, then sprinkler-irrigated to germinate seed Jan 18, 2024 on beds with 84 in. between bed centers and containing 30 lines of seed per bed.  All irrigation water was supplied by sprinkler irrigation.  Treatments were replicated four times in a randomized complete block design.  Replicate plots consisted of 15 ft lengths of bed separated by 3 ft lengths of nontreated bed.  Treatments were applied with a CO₂backpack sprayer that delivered 50 gal/acre at 40 psi to flat-fan nozzles. 
 

 
Downy mildew (caused by Peronospora farinosa f. sp. spinaciae) was first observed in plots on Feb 19  and final reading was taken on February 26, 2024. Spray date for each treatments are listed in excel file with the results.   Disease severity was recorded by determining the percentage of infected leaves present within three 1-ft² areas within each of the four replicate plots per treatment.  The number of spinach leaves in a 1-ft² area of bed was approximately 144. 

The data (found in the accompanying Excel file) illustrate the degree of disease reduction obtained by applications of the various tested fungicides. Products that  provided effective control against the disease include Orondis ultra, Thrive 4 M, Fungout, Cevya, Eject and Zampro. No phytotoxicity was observed in any of the treatments in this trial.

Cultivation is probably the most commonly used method of weed control used here. In addition to immediate gratification, it can eliminate many small weeds. Newly cultivated fields look healthier and are free of weeds. The gratification of cultivation can be short-lived. In the long term, cultivation may be more harmful than good for weed control and soil health.

Most weed seeds are very small and have difficulty making it to the surface alive. Cultivation helps bring small seeds to the surface where they can grow.

Cultivation is also an ideal method to spread and plant many weeds like Bermuda grass and Nutsedge. It also propagates established purslane and other weeds that re-root at the nodes.

Cultivation will uproot and dry out many small weeds but if it is done too close to the crop it can damage roots.

Rarely is cultivation used alone. It is often used in combination with and to incorporate herbicides. Many preemergent herbicides work by creating a chemical barrier at the surface. Cultivation can disrupt this barrier and reduce herbicide efficacy. It not only dilutes the herbicide but breaks up the soil structure so that herbicides, fertilizers and organic matter can leach below the region where they are needed.