2018 Open4st Project Summary

Post date: Oct 11, 2018 11:21:56 PM

Attended the 2018 Woody Crops International Conference

• The Open4st team attended the 2018 Woody Crops International Conference in Rhinelander Wisconsin.  It was an enjoyable and productive event!

• Submitted the Special Publication: Low-Resource Aspen Breeding and Nursery Selection Strategies

• Presented the 2018 Rhinelander Tree Shelter Demonstration and 2018 Open4st Aspen Propagation Project papers in an outdoor demonstration.

2018 Field Trial Plantings

The Open4st team planted on 2 sites in 2018. 

• A 2018 field trial with 216 trees was planted on Weyerhauser property near Escanaba, Michigan.  Plant material consisted of 8 Open4st hybrid aspen clones via 12" dormant cuttings and 1 control family of TxE (P. wettsteinii) 1-0 seedlings protected with 5' staked tree tubes on a 3 year old clear cut site.  The trees were planted at 10' x 10' spacing on 4-tree square plots in 6 blocks with 9 randomized plots in each block.  All relevant field trial data will be stored in the online avw_field_trial database table.

• Table 1 compares dormant cutting survival between the 2018 WY 24 clone field trial and 4 to 6 year Bell nursery 8" dormant cutting survival rates.  Below are comparison observations:

  • The average survival rate of the entire 2018 planting was 79%. The average planting survival rate without the TE control seedlings was 76%.

  • The expectation is that the shorter 8" nursery cuttings should survive better as 12" cuttings on good field sites with good weed control/moisture. The lower survival rate may be caused by the intense site competition, late glysophate application and compromised cutting health due to late fertilizer application in the Bell nursery (past 7/15/17).  Going forward, we hope to nursery test 8", 10" and 12" dormant cutting survival via mediocre rooting clones (eg. 2b25) to better understand cutting length impact under favorable nursery conditions.  Perhaps if 8" and 12" nursery grown cuttings for clone 2b25 root at 54% and 70% respectively then perhaps we could expect the 12" cuttings to root up to 70% in the field dependent upon conditions.

  • The sibling clones 16ab1 and 16ab8 had similar Bell nursery survival rates. The poor performance of 16ab1 may suggest clonal cutting health and hardening or storage issues.

  • The sibling clones 2b22 and 2b25 had the same WY field survival rates yet had 11% Bell suvival rate differences. However, both clones under-performed the Bell survival rates.

  • Clones 1bw6 and 20bs1 rooted nearly 100% at both Bell and WY. Perhaps good rooting rates can overcome some site, cutting and storage issues.

  • The first year survival rates have been recorded and dead trees may be replaced and recorded with the same 12” dormant cuttings in the Spring of 2019.

• There were 40 trees planted on an existing Open4st archive site near Grand Rapids, Michigan.  These bare root 5' hybrid aspens are part of 307 trees to be used as a clonal archive and seed orchard.

• Below is a photo of a 2 year hybrid aspen back cross (clone 8bg9) planted as 5' "deer proof" stock.  Note the in-row weed control and woven textile sleeves used for deer protection:

2018 Nursery Summary

• The 2018 Bell Nursery was irrigated, mulched, fertilized and located on about 1000 square feet with 30" x 4" double row configuration similar to previous years.  See: 2018-Bell-Nursery spreadsheet and 2018 Open4st photos.

• The 8" Dormant cuttings (DC) were planted in rows 30" apart with cuttings spaced 3" to 5" within the row and separated by 4" double rows and MiracleGro Peat moss applied between the cuttings.

• There were 337 F1 25xr P. rouleauiana and 233 6xgg full sib P. grandidentata seedlings grown at Bell in 2018.  Both crosses share the highly figured GG12 P. grandidentata male parent.

• There were 1805 feet of field grade cuttings grown at the Bell nursery in 2018. 

• The average survival rate of cuttings and mini-stools was 80%.

• There were 34 TxE (P. wettsteinii) clones each planted with 4 - 8" dormant cuttings (136 total cuttings planted).  Four clones had single surviving rooted trees that will be retried in 2019.  This doesn't appear to be a promising strategy since only one rooted tree originated from a mid-stem cutting suggesting root collar influence of lower stem cuttings.

• There were 480 dormant cuttings planted, yielding 288 trees with 609 field grade cuttings and 42 plus trees scheduled for retesting.

• A 2 foot pruned "bush stock" concept will be tested by cutting back rooted cuttings to 18" tall in mid-July then out plant them with an 18" woven textile sleeve.  Next year they will also be pruned back in August to 22"  The idea is that a June planted bushy aspen may be pruned back somewhat by deer/rabbits but not killed and eventually grow in later years.  It could be less expensive than using 5' staked tree tubes or 7' trees and allow poor rooting clones to be started in a greenhouse as small 4" cuttings and transplanted to the field as healthy 1-0 stock.  The drawback to this concept is the overhead of obtaining this stock in the nursery.  Perhaps it would be more efficient to breed clones that root well from cuttings and investigate processes to grow them in the field.

• More tests will be conducted in 2019 including the planting of 14", 18" and 24" dormant cuttings with white semi-transparent fabric ventilated sleeve halves, some covering several inches above the cutting with a 3' bamboo stake.  This approach will be similar to the "bush stock" but should be operationally more efficient, since it would not require a 1-0 nursery stock. It may require an additional year in the field to survive browsing and the use of good rooting clones.

• The Bell nursery planting was divided into 24 categories or replications, each having a distinct type of treatment or test.  Table 2 lists the 2018 Bell nursery summary by replication.

• There were 20 clones including the control clone DN34 that were identified with good field and nursery performance in terms of propagation, form, field vigor and disease resistance.  Table 3 lists these "plus trees" with their associated nursery dormant cutting propagation rates, total field grade 12" cuttings and field metrics.  These selections represent 11 different families having 12.5% to 62.5% native P. grandidentata parentage, root well from stem cuttings and most have been field tested for at least 2 years.  These materials will be the focus of 2019 field trials, Bell nursery and cooperator distribution. 

• In 2019 we will propagate 8", 10" and 12" dormant cuttings in the nursery to compare survival/growth differences in a fertile, irrigated nursery setting.  This may help understand the differences between nursery survival of the 8" cuttings to longer (10" to 12") lengths typically used in field plantings.

• For more details see the r4st database and the 2018 Nursery Stock Summary

• Below is a photo of the 2018 Open4st Bell nursery:

2018 Key Propagation Observations

• We have observed that field planting of large 1-0 7' trees are harder to grow, store and may develop "floppy tops" since they don't grow thick, supportive stems in the nursery.  This may not be an ideal process from a larger scale, operational standpoint.  Perhaps planting 14" dormant aspen cuttings could be a better field operational strategy. The obvious trick is to have aspen clones that can root consistently like other cultivated poplars (e.g. DN34), and be able to start them in the field in an economical, large scale fashion.

• We moved closer to this goal in 2018 as we tested clones from the P. x rouleauiana family, 25xr. There were 71 25xr clones represented by 4 - 8" dormant cuttings planted from each ortet whip. Surprisingly 82% of these clones rooted 100% (4 out of 4 cuttings rooted). However, most of these AG clones didn't root consistently and may not long term. The infamous AG clone ‘Crandon’ (P. × rouleauiana) rooted 25% in my nursery and less than 50% for Dr. Hansen (USFS). Therefore I could expect similar rooting from most of these clones.

• I recently spoke with a colleague about selecting P. Deltoides for good rooting. He observed his best clones root more consistently when they have more adventitious dormant cutting side rooting. Sure enough my best rooting established aspen clones have consistent adventitious rooting (e.g. clone 1bw6) having an average adventitious sum of root diameter of about 24 mm. Fortunately, we found one clone this year (25r49) with similar adventitious rooting from 4 - 8" dormant cuttings. Going forward, we will track adventitious rooting in the nursery via the "avg_ar_score" metric. I am convinced that our hybrid aspen field plantings need good rooting clones to be operationally successful.

• Clone 1bw6 is an open pollinated selection from the Canadian clone cag204. It has rooted 100% (29/29) over 3 years in the nursery with 8" dormant cuttings. It has great adventitious rooting and has been vigorous in the field. We are excited for 2019 as we have 337 more 25xr ortets (P. x rouleauiana) to test for rooting and figure.