Almond & Other Stonefruit Summary
The project included 13 orchard replant trials (Table 1). Each trial tested pre-plant soil treatments for management of replant problems where orchards of almond, peach, or plum were removed and replaced.
Replant disease (PRD), which is a poorly defined soilborne complex that suppresses growth and yield in successive plantings of almond and stone fruits, was an expected replant problem at all sites. The ring nematode was expected to be an important replant problem in two of the trials established recently on sand-textured soils infested with the pest in Merced County.
There was a progression of treatments in the trials (Table 1). The early emphasis was on fumigant alternatives to MB (chloropicrin, 1,3-dichloropropene (1,3-D), iodomethane (IM), and mixtures of chloropicrin with 1,3-D and IM, and yields were available from many of these trials (see links to Figures in Table 1). The fumigants containing chloropicrin were very effective for controlling PRD, more so than MB.
The trials progressed to testing reduced fumigant rates per orchard acre while retaining treatment efficacy; spot shank fumigation using GPS-controlled shanks and spot drip fumigation were developed and tested. The spot treatments were found to adequately manage PRD while reducing fumigant emissions compared to conventional strip and broadcast fumigation. Still, spot fumigation will require adaptation and commercialization before it is used widely.
Short-term sudan grass rotations were found to improve growth and productivity of replanted peach orchards, but the rotation is not as effective as pre-plant soil fumigation. Testing effects of irrigation intensity (i.e., by using treatments that applied amounts of water ranging from 71 to 127% of crop ET) revealed that although over- or under-irrigation aggravated severity of PRD, optimal irrigation alone did not adequately control PRD.
Our most recent trials extended the spot treatment approach to non-fumigants. We included spot treatments with mustard seed meal and steam in collaboration with Brad Hanson and Steve Fennimore. Growth data will soon be available for these trials.
|Planting year||Location||Replanted Crop/rootstock||Soil Texture1/||Preplant problem(s)||Yield data2/|
|2004||Madera, Ave 7||Almond/NG||L||PRD||Fig.1|
|2007||Firebaugh, Ave 7.5||Almond/NG||FSL||PRD||Fig.2|
|2008||Arbuckle, Green Bay||Almond/NG||SL||PRD||none|
|2008||Madera, Ave 16||Almond/NG||SL to LS||PRD||Fig.3, Fig.4, Fig.5|
|2009||Reedley, Floral Ave.||Peach/NG||FSL||PRD||Fig.7|
|2010||Madera, Ave 14||Almond/NG||L to LS||PRD||none|
|2010||Merced||Almond/Viking||S/SS||Ring & Les Nem., PRD||none|
|2011||Merced||Almond/NG||S||Ring Nem., PRD||none|
|2011||Parlier, USDA||Prunus rootstocks||FLS/SS||PRD||none|
|2011||Bakersfield (proposed 2011)||Almond/NG vs. Almond/Han.||SL||PRD||none|