Evaluation of Herbicide Sensitivity and Resistance in Cold-Hardy Grapevine Cultivars
Status:  Planned - Updates will be posted at the bottom of the protocol page here

 

1. Objective

To quantify the visual injury, physiological response, and recovery rates of various cold-hardy white and red grapevine cultivars when exposed to simulated drift concentrations of Dicamba, Roundup (Glyphosate), and 2,4-D.
 

2. Background / Rationale

Herbicide drift from neighboring row-crop operations remains a primary constraint for vineyard establishment and longevity in prairie regions. While the sensitivity of traditional vinifera is well-documented, there is limited peer-reviewed data regarding the specific resistance levels of newer cold-hardy hybrids like Clarion or Crimson Pearl under prairie conditions.

 

• Observations: Frequent grower reports of significant damage from neighboring soybean or corn applications.

• Need: Identifying "low-sensitivity" cultivars could influence future vineyard site selection and cultivar choice for high-risk areas.
   

3. Hypothesis

Cultivars will exhibit distinct, measurable levels of resistance and recovery based on their genetic parentage.

• Systemic herbicides (Roundup) will cause more terminal shoot death.

• Growth-regulator herbicides (2,4-D and Dicamba) will produce varying levels of leaf strapping and cupping.

• Certain hybrids will demonstrate significantly faster recovery of vigor compared to more sensitive varieties.
   

4. Cultivars Tested

White Cultivars : La Crescent, Brianna, Edelweiss, Itasca, Prairie Star, Frontenac Blanc, Vignoles, Clarion

Red Cultivars: Frontenac, Marquette, Petite Pearl, Crimson Pearl, St. Croix, Verona

 

5. Experimental Design

• Treatment Groups: Vines will be exposed to ultra-low "drift-level" concentrations (e.g., 1/100th or 1/1000th of field rate) of each herbicide.

• Control Group: Vines receiving only standard vineyard maintenance.

• Layout: Randomized block design to ensure each cultivar is represented in both treatment and control groups.

• Site Documentation: USDA Zone, soil type (Loamy Clay), and high-wind exposure characteristics will be recorded.
   

6. Treatment Application

• Timing: Application will occur during the rapid shoot growth phase (pre-bloom) when vines are most sensitive to hormone-based herbicides.

• Method: Targeted hand-sprayer application to simulate drift patterns rather than direct over-the-top spraying.
   

7. Data Collected

Herbicide Injury Assessment

• Visual Rating Scale: 0 (No injury) to 10 (Vine death).

• Symptom Tracking: Specific documentation of leaf cupping (Dicamba), strapping (2,4-D), and chlorosis/terminal yellowing (Roundup).

• Recovery Rate: Weekly monitoring of new growth to determine if the vine "grows out" of the injury or suffers prolonged stunting.

Growth Metrics

• Shoot Elongation: Comparison of shoot length between treated and control vines.

• Fruit Set Impact: Observations on cluster abortion or poor fruit set following exposure.
   

8. Timing

• Late Spring: Baseline vigor measurements and initial treatment application.

• Early Summer: Weekly injury ratings and recovery observations.

• Post-Harvest: Evaluation of cane maturation and potential impact on winter hardiness.
   

9. Limitations

• Drift Simulation: Micro-applications may not perfectly replicate the dynamics of real-world chemical drift.

• Environmental Interaction: Temperature and humidity at the time of exposure can significantly alter herbicide volatility and uptake..
   

10. Sensitivity Protocol (Post-Exposure)

Following exposure, the following "Vulnerability Table" will be used to categorize cultivar response: