Spot-application of fungicide for wild blueberry using an automated prototype variable rate sprayer

Wild blueberry producers apply fungicide uniformly without considering significant bare spots in the field. The wrong or over use of fungicide in bare spots results in an increased cost of production and threatens the environment. An automated prototype variable rate (VR) sprayer was used for spot-application (SA) of Chlorothalonil (Bravo®) fungicide in a wild blueberry field. Eighteen 6.1 m wide test tracks were selected in the field and bare spots were mapped using a real-time kinematics-global positioning system (RTK-GPS). Six plots were selected randomly for three different application rates. Water sensitive papers (WSP) were placed in foliage and bare spots in SA and uniform-application (UA) tracks. The percent area coverage (PAC) of WSP with both SA and UA in foliage and bare spot areas were calculated. Plant growth parameters were measured from all 108 randomly selected plots in SA, UA and control (CN) tracks for comparison. Plant images were taken over six selected plots in each of the 18 tracks. Images were analyzed using custom developed software to calculate the percentage of green pixels (PGP) for determining the effect of Bravo® on plant health. Fruit yield parameters were also measured from selected plots for comparison. Non-significance of the t test for SA versus UA plant targets’ PAC indicated that there was no significant bias in the SA with saving (9.90–51.22 %) and SA was accurate. Bravo® did not show any significant difference on plant growth parameters among SA, UA and CN. However, PGP, floral bud and harvestable yield of SA and UA were significantly increased over CN. Therefore, a VR sprayer could be used for SA of fungicides in wild blueberry cropping system to reduce chemical usage and maintain crop productivity.

[1]  Qamar Uz Zaman,et al.  Original papers: Development of prototype automated variable rate sprayer for real-time spot-application of agrochemicals in wild blueberry fields , 2011 .

[2]  Réjean Tremblay,et al.  Potential link between exposure to fungicides chlorothalonil and mancozeb and haemic neoplasia development in the soft-shell clam Mya arenaria: a laboratory experiment. , 2009, Marine pollution bulletin.

[3]  Michaud Ma,et al.  Precision pesticide delivery based on aerial spectral imaging , 2008 .

[4]  Qamar Uz Zaman,et al.  An automated yield monitoring system II for commercial wild blueberry double-head harvester , 2012 .

[5]  Qamar Uz Zaman,et al.  Development of Color Co-Occurrence Matrix Based Machine Vision Algorithms for Wild Blueberry Fields , 2012 .

[6]  Qamar Uz Zaman,et al.  Automated, low-cost yield mapping of wild blueberry fruit. , 2010 .

[7]  Marc-André Michaud,et al.  Precision Pesticide Delivery Based on Aerial Spectral Imaging , 2006 .

[8]  Qamar Uz Zaman,et al.  Estimation of wild blueberry fruit yield using digital color photography. , 2009 .

[9]  Qamar Uz Zaman,et al.  Variable rate granular fertilization of citrus groves: spreader performance with single-tree prescription zones. , 2005 .

[10]  W. Ernst,et al.  The toxicity of chlorothalonil to aquatic fauna and the impact of its operational use on a pond ecosystem , 1991, Archives of environmental contamination and toxicology.

[11]  D. Percival,et al.  Foliar disease impact and possible control strategies in wild blueberry production. , 2009 .

[12]  Qamar Uz Zaman,et al.  Detecting Bare Spots in Wild Blueberry Fields Using Digital Color Photography , 2010 .

[13]  Travis Esau,et al.  DEVELOPMENT AND EVALUATION OF A PROTOTYPE VARIABLE RATE SPRAYER FOR SPOT-APPLICATION OF AGROCHEMICALS IN WILD BLUEBERRY FIELDS , 2012 .