This study was conducted at the JV farms at Gila Valley. Lettuce variety ‘Guapo’ was seeded, then sprinkler-irrigated to germinate seed on September 19, 2023, on double rows 12 in. apart on beds with 42 in. between bed centers.  Rest of the irrigation was supplied by furrow irrigation or rainfall. Treatments were replicated five times in a randomized complete block design. Each replicate plot consisted of 25 ft of bed, which contained two 25 ft rows of lettuce. Plants were thinned on October 9, 2023 at the 3-4 leaf stage to a 12-inch spacing. Treatment beds were separated by single nontreated beds. Treatments were applied by incorporating in soil before seeding or with a tractor-mounted boom sprayer that delivered 50 gal/acre at 100 psi to flat-fan nozzles spaced 12 in apart.

 
Fusarium wilt (caused by Fusarium oxysporum f. sp. lactucae ) rating was done in the field by observing the typical symptom of lettuce wilt. Confirmation was done by cutting the cross section of roots. Disease scoring/rating was done on December 6, 2023. 
 
The data in the table illustrate the degree of disease control obtained by application of the various treatments in this trial. The disease pressure was extremely high in 2023, and most treatments showed little or no control against the disease. The treatments that showed some activity were Bexfond, Cevya, Rhyme, and Serifel. Plant vigor was normal and phytotoxicity symptoms were not observed in any treatments in this trial.

An increasingly diverse number of minor acreage specialty crops are grown in this region every year. Managing some of these crops can be difficult without local experience. Crops in the same family often have similar growth habits, pest problems and fertility requirements and it can be helpful to know what botanical family they are in. There are almost no pesticides registered for some of these crops because of the limited acreage but their response to pesticides is often, but not always, similar to that of other crops in the same family. Kerb (pronamide), for instance, is generally safe to crops in the composite family (lettuce, artichokes, radicchio etc.) but is harmful to crops in the brassica family( broccoli, bok choy, etc.) The question of Balan safety to endive came up this week. Prefar and Kerb are registered on this crop but not Balan. Endive is in the same botanical family as lettuce. This is the Aster, sunflower or composite family. It is the largest family of flowering plants. Endive is in a different genus, however, than lettuce. The genus is chichorium(chicory) genus while lettuce is in the lactuca genus. Escarole and radicchio are types of endive. It is unclear if Balan is not registered on endive because of crop safety or other registration issues. Herbicides are sometimes not registered on certain crops because required studies have not been completed and a tolerance has not been established. We are currently evaluating the safety of balan to endive and escarole and should have an indication in about a week. We have put the following table together to help identify the botanical families many of the crops grown here belong to.

Crop Families