Summary
The year 2020 marked the third year in a row that cold weather played a detrimental role in the farming of grapes at Johnston Vineyards and much of the Annapolis Valley. June 4, 2018 brought a severe late spring frost (the worst since 1958) that eventually resulted in the loss of 1/3 of our vines. The growing season of 2019 was shortened by a late spring and early fall frost and the winter of 2020 was punctuated by a temperature inversion down to -25 C on February 15. Vine damage caused by the freeze of June 4, 2018 continued to result in vine loss into 2020. The original damage occurred in vinifera as well as the more sensitive hybrids varieties like NY Muscat, Seyval and Vidal. It became apparent that selection of vineyard location is vital to the longterm survival of grape vines, especially sensitive vinifera and hybrids. What was also apparent was the detrimental effects of the vineyard microenvironment including wet areas and depressions in the land contours. Aggressive nutritional management provided by Agromart Truro may have reversed the death spiral noted in the less hardy hybrids following the June 4, 2018 freeze. Unfortunately this was not possible without discontinuing organic certification.
Major winter 2020 bud kill in the vinifera
The LTE10 reported by the Kentville Research & Development Center (KRDC) for Feb 17-18 was -15.9 C which represented significant de-acclimation from Feb 3-5 (-19.9). The temperature on Feb 15 at the weather station at KRDC was -21.7 C but when measured at 1 meter above the ground was -24.6 C due to a temperature inversion. Temperatures were higher in the western end of the Annapolis Valley. Due to the low temperature in the eastern end of the valley primary vinifera bud viability was close to 100% whereas in the Western Valley there was little bud loss. Bud samples taken at Johnston Vineyards after the freeze on Feb 15 showed about a 90% primary and secondary bud kill in the vinifera. The goal of pruning of the vinifera was to preserve at least 2 fruiting canes on each trunk. All canes will be tied down by the end of May.
Longterm vine survival after the freeze of June 4, 2018
There was no long term damage from the June 4, 2018 freeze to the two Minnesota developed vines Marquette and Petite Pearl. Twenty percent of the 2 year old Petite Milo died in the freeze but the survivors rebounded nicely. Unfortunately the buds consistently open 2 weeks before other varieties and will be prone to spring frost damage in future. Of the french hybrids NY Muscat, Seyval Blanc and Vidal suffered long term damage from the 2018 freeze and about 40% of the plants eventually died. The vinifera suffered the most cold damage with the Chardonnay 548/3309 being the least affected of the vinifera. Pinot Noir was the most affected with many young plants killed outright. The Cabernet Foch were badly damaged by the cold weather and suffered from extensive crown gall. The Geisenheim 318 reaction to the freeze was much like the Petite Milo with significant loss of the 2 year old vines while the survivors recovered nicely. There is no L’Acadie planted at Johnston Vineyards.
Vine survival also depended on vine location in the vineyard. For example there is a band of land across the mid portion of block A where the vines struggle and many have died. This is more apparent in the plots planted with borderline hardy varieties. Several soil analyses failed to find any imbalance in soil nutrients. Soil structure was abnormal in this region with heavy clay present and no soil microbes (there were few microbes anywhere in the vineyard). In general, it would appear that vinifera growth at Johnston Vineyards was sensitive to decades of land neglect prior to the vineyard planting. Vines located in dips in land contour (areas where frost and cold air accumulate) took a beating. Vines located along the outer rows suffered (is this due to failure to spread fertilizer on both sides of the row?) Vines located in areas of reduced water drainage suffered (despite the vineyard being drain tiled). Vinifera were especially hard hit in wet areas. The bottom line is that careful site selection is vital to successfully farming of sensitive grape varieties in Nova Scotia.
The young chickens are getting used to the great outdoors.
Nutrition in freeze damaged vines
Based on SAP testing of young and old vine leaves, it was concluded that root damage in many of the vines prevents adequate uptake of essential nutrients. Biomax, an Agro-K product which contains nutrients and enzymes to stimulate growth of beneficial bacteria and fungi improves root health and will be added to the soil this spring. Sysstem Mg and Sysstem Ca provide rapid absorption into the roots via a foliar spray and will be applied early in leaf development. Granular fertilizer consisting of a prill of potash with boron attached (called Aspire) and Mesz which consists of N-P prills with Ca, S and Zn attached was applied. The final blend was 10-15-10 6.5Ca, 8S, .3Zn, and .2B.
It was difficult to adequately support vine nutrition within the confines of organic certification
Since organic certification did not allow for some of the desired nutrients to be efficiently applied, organic certification was discontinued after 1 year of eligibility. Weeds could not be adequately control with the grape hoe which also appeared to be associated with trunk damage to the younger vinifera vines (this was likely aggravated by the use of grow tubes that left the rapidly growing trunk susceptible to blunt trauma from the hoe). Organic standards were maintained for foliar nutrients and pesticides to reduce health risks and to ease the path back to organic certification.
Replanting
Replanting of the vinifera has been undertaken despite the evidence that Johnston Vineyards is susceptible to cold weather. The hope is that the weather will cooperate for a few years while the vines mature enough to ward off the occasional cold spell. Two acres of Cabernet Foch will be replaced in L’Acadie this spring. Cab Foch is extremely susceptible to cold complicated by rampant growth of crown gall.
Hilling up to protect vine graft sites
It was decided not to hill up the vines last fall. This is traditionally done to protect the graft site. Fairly severe soil erosion occurred each winter as snow thawed and ran down the frozen trenches left along each side of the vine rows. Moreover, the graft sites were frequently left uncovered by mid winter due to ongoing erosion defeating the original purpose of hilling up. Hilling up appeared to have little beneficial effect on vine survival with crown gall and dead plants found each spring. Hilling up did result in good weed control in early spring and was applied to both hardy hybrids and vinifera for this reason each fall until 2019.
