Fresh Pruning Wounds Research Articles

Seasonal Susceptibility of Sweet Cherry Pruning Wounds to Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata.

Fungal canker pathogens commonly infect trees at pruning wounds leading to branch dieback and loss of productivity in sweet cherry orchards. However, the seasonal susceptibility of sweet cherry pruning wounds to Calosphaeria pulchella, Cytospora sorbicola, and Eutypa lata is not well understood. This study compared the susceptibility of sweet cherry pruning wounds made during the dormant season (January) and the postharvest season (late May to June) to infection by main canker pathogens in California. Field trials were conducted in three cherry orchards and trees were pruned at the different periods over 2 years. Fresh pruning wounds were inoculated with spores of each pathogen, and pathogen recovery was assessed through microbiological isolations at 3 to 4 months after inoculations. Pruning wounds made in late May and June resulted in significantly higher infection by Cal. pulchella compared to pruning wounds made in January. Pruning wounds made during both seasons were generally equally susceptible to Cyt. sorbicola and E. lata infections. However, there was one orchard where dormant pruning wounds were more susceptible to infection by E. lata and there was one particularly cold winter where Cyt. sorbicola did not infect pruning wounds. Overall, our findings suggest that Cal. pulchella infections of cherry pruning wounds are more likely to occur during periods of warm temperatures such as late spring and early summer. However, infections by Cyt. sorbicola and E. lata can occur year-round if inoculum is present and if winter temperatures are not abnormally low for California. Finally, our results suggest that the emergence of Cal. pulchella as a major canker pathogen of sweet cherry in California may be the result of a shift from dormant to after-harvest pruning of sweet cherry trees.

Duration of the susceptibility of pruning wounds of different ages to infections by Phaeomoniella chlamydospora on grapevine cv. Cabernet Sauvignon in Central Chile.

Grapevine trunk diseases (GTDs) are one of the most important phytosanitary problems that affect grapevines (Vitis vinifera) worldwide. In Chile, Phaeomoniella chlamydospora is the major fungal trunk pathogen associated with GTDs. In the vineyards, the natural infections by P. chlamydospora are associated with air-borne conidia dispersed onto fresh pruning wounds from pycnidia. These pruning wounds are considered an important entrance for fungal trunk pathogens such as P. chlamydospora in the host in the field. However, the duration of the susceptibility of grapevine annual pruning wounds to P. chlamydospora is still unknown in Chile. Therefore, this study aimed to evaluate the period of susceptibility of pruning wounds of different ages to artificial infection of P. chlamydospora on grapevine cv. Cabernet Sauvignon, Central Chile. Artificial inoculations of a conidial suspension (105 conidia/mL) of P. chlamydospora were used to determine the susceptibility of pruning wounds of different ages, from 1, 15, 30, and 45 days after pruning. The experiments were conducted on lignified cuttings in a greenhouse, and on vine spurs in two vineyards (Buin and Nancagua, Central Chile) during two consecutive seasons. The results indicated that the pruning wounds of grapevine cv. Cabernet Sauvignon were very susceptible to infections by P. chlamydospora, with a percentage of pruning wounds infected from 97 to 71% for cuttings, and 96% to 60% for spurs, during the first 15 days after pruning. However, the susceptibility of pruning wounds of different ages in cuttings and spurs of grapevine, generally decreased as the time from pruning to inoculation increased. Moreover, the pruning wounds the pruning wounds remained susceptible to artificial inoculation by P. chlamydospora for up 45 days after pruning with percent of wounds infected from 8.0 to 12.2, and 8.3 to 18.8% on cuttings and spurs of grapevine, respectively. Finally, this study constitutes study constitutes the first research focalized on the susceptibility of pruning wounds of various ages of grapevine cv. Cabernet Sauvignon to artificial inoculations by P. chlamydospora in Central Chile.

Pruning practices influence infection and dissemination of Calosphaeria pulchella, the cause of Calosphaeria canker of sweet cherry

Calosphaeria canker of sweet cherry, caused by Calosphaeria pulchella , is a limiting factor for sweet cherry production, but the role of pruning practices on pathogen dissemination remains unknown. Three experimental treatments were compared during summer and winter seasons, to assess their effects on pathogen transmission. The treatments were: i) using disinfected pruning shears; ii) pruning shears used to cut through diseased branches before each subsequent cut (non-disinfected pruning shears); and iii) artificial inoculation of fresh pruning wounds with C. pulchella . Six months after pruning, branches were cut from trees for disease assessment and fungal isolation. Pruning with non-disinfected pruning shears increased disease incidence and severity, compared with the use of disinfected shears. Artificially inoculated branches gave the greatest disease incidence and severity. Results from the various treatments were consistent for both winter and summer pruning. These confirm that frequent disinfection of pruning tools is advised for the effective management of Calosphaeria canker of sweet cherry.

Protection of Grapevine Pruning Wounds against Eutypa lata by Biological and Chemical Methods

Eutypa dieback, caused by the fungus Eutypa lata, is a serious disease of grapevines that infects mainly through pruning wounds. The aim of this study was to evaluate the in vitro efficacy of fungicides from various chemical groups against E. lata, as well as the in vivo efficacy of the most effective fungicides and selected bacterial and fungal antagonists of E. lata, in grapevine pruning wound protection trials. In vitro studies revealed that flusilazole, tebuconazole, benomyl, fenarimol and myclobutanil were the most effective fungicides to inhibit mycelial growth of E. lata. Two field trials were conducted, one subjected to artificial inoculation and the second to natural infection only. In the first, benomyl, flusilazole and commercially available Trichoderma harzianum-containing products and an experimental Bacillus subtilis strain were applied to fresh pruning wounds. Two Cabernet Sauvignon vineyards were pruned in August 2001 and 2002 and immediately treated and inoculated with a spore suspension of E. lata one day later. Isolations were made from the treated pruning wounds after 12 months to assess the effectiveness of the treatments. The fungicides benomyl and flusilazole were the most effective treatments, although the Trichoderma treatments T77 and Trichoseal spray caused a significant reduction in E. lata infection. In a second trial, pruning wounds of Cabernet Sauvignon, Sauvignon blanc, Red Globe and Bonheur were treated with the Trichoderma products Vinevax (= Trichoseal spray) and Eco77 (= T77) in August 2005 and 2006, subjected to natural infection only and evaluated after seven months. Vinevax and Eco77 not only reduced E. lata, but they also reduced the incidence of other grapevine trunk disease pathogens.

New understanding on infection processes of Valsa canker of apple in China

Apple canker caused by Valsa mali is a destructive disease that causes serious economic losses in China. In this study, the dynamics of release of conidial masses (cirri) in apple orchards were studied in different seasons, and in laboratory tests the effects of temperature on conidial germination were determined. Using artificial inoculations in the field, the influence of the pruning process on year-round disease development, and the possibility of the pruning saws carrying conidia of V. mali were tested to determine disease transmission in the winter months. Conidial masses released from pycnidia demonstrated strong adaptability to the changing environment. Conidial exudation from pycnidia could last up to a year and take place even in the winter, in the period when the bark was wet. The germination rate of conidia reached 90 % after 6 days incubation at 5 °C and 50 % after 19 days at 0 °C. Infection rates of conidia in different seasons were determined in a 3-year experiment. Fresh pruning wounds were more susceptible to infection than old wounds, and conidia were able to infect apple trees and induce canker lesions at different times of the year, and especially in winter. Pruning in early winter may promote heavy infections of apple by V. mali and could play an important role for the spread of the disease.

Efficacy of paste and liquid fungicide formulations to protect pruning wounds against pathogens associated with grapevine trunk diseases in Chile

Trunk diseases are important on grapevines (Vitis vinifera L.) in most countries where grapevines are grown. In Chile, Diplodia seriata, Inocutis sp. and Phaeomoniella (Pa.) chlamydospora are the most prevalent pathogens associated with this syndrome. It has been demonstrated that fresh pruning wounds are the main infection route for fungal trunk disease pathogens. The objective of this study was to evaluate the efficacy of paste and spray fungicide applications in protecting pruning wounds against D. seriata, Inocutis sp. and Pa. chlamydospora on ‘Cabernet Sauvignon’ grapevines in two important Chilean grapevine production areas. The fungicides used in this study were benomyl, pyraclostrobin, tebuconazole, and thiophanate-methyl, which were applied as paste and liquid fungicide on fresh pruning wounds pre- and post-inoculation with mycelium plugs of the different fungal pathogens used in this study. The efficacy of the fungicides was assessed by measuring the length of the discoloration of the vascular system and percent re-isolation obtained on fresh pruning wounds. The results obtained demonstrate that infections caused by D. seriata, Inocutis sp. and Pa. chlamydospora can be significantly reduced using both paste and spray applications of benomyl, pyraclostrobin, tebuconazole and thiophanate-methyl and that the paste formulations provided a better control than spray applications. Regardless of the fungicide and application method used, the pre-inoculation treatments (performed 24 h before inoculation) resulted in better control than the 24 h post-inoculation treatments. The current study showed that Inocutis sp. can induce vascular discoloration on grapevine spurs. This study supports a broader use of benzimidazole fungicides for the control of the devastating trunk diseases in all grape productions worldwide.

Evaluation of biocontrol agents for grapevine pruning wound protection against trunk pathogen infection.

Trunk diseases of grapevine are caused by numerous pathogens, including Eutypa lata , Phaeomoniella chlamydospora , and species of Botryosphaeriaceae (incl. Botryosphaeria and aggregate genera), Phomopsis and Phaeoacremonium . Since infections occur mainly through pruning wounds, that have been shown by previous research to stay susceptible for up to 16 weeks after pruning, long-term pruning wound protection is required for prevention of infection. This study evaluated several biocontrol agents against a range of trunk disease pathogens in dual plate laboratory trials to determine macroscopic and microscopic interactions. The biocontrol agents had a substantial effect on all the pathogens, with a wide range of macroscopic and microscopic interactions observed. The best performing biocontrol agents were tested in two field trials. Fresh pruning wounds were treated with benomyl, Trichoderma products (Biotricho®, Vinevax® and ECO 77®) and isolates (USPP-T1 and -T2, identified as T. atroviride ) and Bacillus subtilis . Seven days after treatment the pruning wounds were inoculated by spraying with spore suspensions of Neofusicoccum australe , N. parvum , Diplodia seriata , Lasiodiplodia theobromae , Eutypa lata , Phaeomoniella chlamydospora or Phomopsis viticola . Eight months after inoculation, the treatments were evaluated by isolation onto potato dextrose agar. The efficacy of the biocontrol agents was in most cases similar or superior to that observed for benomyl. Isolate USPP-T1, in particular, was very effective, reducing incidence of Ph. viticola , E. lata , Pa. chlamydospora , N. australe , N. parvum , D. seriata and L. theobromae by 69, 76, 77, 78, 80, 85 and 92%, respectively. This is the first report of biological protection of grapevine pruning wounds against this group of grapevine trunk disease pathogens.

Histo-pathology study of the growth of Trichoderma harzianum , Phaeomoniella chlamydospora and Eutypa lata on grapevine pruning wounds

Protecting grapevine pruning wounds by inoculating them with Trichoderma spp. can preventinfection from trunk disease pathogens. The growth and interactions of both, the biological control agent Trichoderma spp. and the vine pathogens, are not well understood. Green fluorescent protein (GFP)-labelled Trichoderma harzianum and red fluorescent protein (DsRed)-labelled T. harzianum , were dual-inoculatedwith Phaeomoniella chlamydospora (DsRed) or Eutypa lata (GFP) on fresh pruning wounds of one-year-oldCabernet Sauvignon and Sauvignon blanc shoots. The inoculated fungi were recovered from varying depthswithin the shoots at 30-day-intervals for 90 days. Trichoderma harzianum suppressed the pathogens and grew deeper in the presence of the pathogens than when it was singly inoculated; possibly an indication of pathogen recognition and competitive response. Eutypa lata was completely eliminated from Sauvignon blancin dual-inoculated canes after 90 days. The mycelium of P. chlamydospora (DsRed) grew extensively in thexylem vessels and possibly contributed to vessel occlusion. Phaeomoniella chlamydospora and E. lata caused blockage of the vessels and thickening of the vessel walls. Grapevine wood produced both tyloses and gums (gels) that blocked xylem vessels as a result of infection. A thickening of the cell walls of xylem fibres occurredonly in E. lata -inoculated shoots, indicative of a different mode of pathogenesis from P. chlamydospora .

Grapevine cultivar variation to pruning wound protection by Trichoderma species against trunk pathogens

Using Trichoderma species to protect grapevine pruning wounds from trunk disease pathogensis one of the options available for managing grapevine trunk diseases. The growth and persistence of Trichoderma species in the pruning wound and the resulting control effect may depend on intrinsic wound factors and hence may vary between cultivars. Cultivar variability to pruning wound protection by Trichoderma species was evaluated in eight wine grape (Cabernet Sauvignon, Chardonnay, Chenin blanc, Colombar, Merlot,Pinotage, Sauvignon blanc and Shiraz) and four table grape (Prime, Red Globe, Thompson Seedless andVictoria) cultivars. Two strains of Trichoderma atroviride (USPP-T1 and USPP-T2) separately or in combinationand Eco 77® a registered pruning wound biocontrol agent based on T. harzianum , were applied to fresh pruning wounds of spur-pruned wine grapevines and cane-pruned table grapevines. Trichoderma spp. and a variety of trunk pathogens, Phaeomoniella chlamydospora and species of Phaeoacremonium , Phomopsis , Botryosphaeriaceae and Diatrypaceae, were isolated from the pruning wounds eight months after treatment. Significant treatment × cultivar interactions (P 0.50;P<0.05) though not in Chardonnay (r=0.37; P=0.11), Pinotage (r=-0.12; P=0.62), Sauvignon blanc (r=0.26;P=0.26) and Victoria (r=0.29; P=0.22). It was concluded that the wound protection effect of Trichoderma spp.is also dependent on the Trichoderma -grapevine interaction and is not only due to the suppressive effect of Trichoderma spp. on the pathogens.

Temporal spore dispersal patterns of grapevine trunk pathogens in South Africa

Trunk disease pathogens of grapevines, viz. Phaeomoniella chlamydospora, Eutypa lata and several species in Botryosphaeriaceae, Phaeoacremonium and Phomopsis are known to infect fresh pruning wounds by means of air-borne inoculum released after rainfall or prolonged periods of high relative humidity. Recent surveys have demonstrated that most or all of these pathogens are present in climatically diverse grape growing regions of South Africa. However, the factors controlling spore dispersal of these pathogens in vineyards were largely unknown. To address this question, spore trapping was done in a Chenin Blanc vineyard in the Stellenbosch area, South Africa, for 14 weeks during the grapevine pruning period from June to mid-September of 2004 and 2005. Hourly recordings of weather data were done by a weather station in the row adjacent to the spore trap. Spores of E. lata and Phomopsis and species in Botryosphaeriaceae were trapped throughout the trapping periods of 2004 and 2005, with higher levels of trapped spores recorded in 2005. The spores of all three pathogens were trapped during or after periods of rainfall and/or high relative humidity. In neither of the 2 years were spores of Pa. chlamydospora or Phaeoacremonium spp. trapped. Results indicated that spore event incidence, as well as the amount of spores released during a spore event of above-mentioned pathogens, were governed by rainfall, relative humidity, temperature and wind speed prior to and during the spore events.

Pruning and cypress canker in New Zealand

In New Zealand, the planting of cypresses is hindered by cypress canker disease caused by Seiridium cardinale (W.W. Wagener) B. Sutton & I.A.S. Gibson and S. cupressi (Guba) Boesew.). Pruning is widely practiced in established plantations to improve timber quality, although knowledge of its effect on disease incidence remains imperfect. Stubs of freshly cut branches on 275 trees of Cupressus macrocarpa Gordon & Leyland were inoculated with an isolate of either S. cardinale or S. cupressi to investigate the potential for pruning wounds to act as infection courts. In total, 75% of stubs inoculated at the edge, and 60% of those inoculated at the centre, became infected and produced stem cankers after 1 year, whereas cankers were formed on only 2% of non-inoculated control stubs. Incidence of cankers differed significantly between isolates. A second experiment was conducted at the same site 2 years later when stand infestation had increased, this time without inoculating but instead relying on ambient field inoculum. Stem cankers were produced on 11% of stubs on 162 trees, as a result of natural infection following pruning during periods of light rain in spring and summer. This investigation confirmed the ability of Seiridium species to invade through fresh pruning wounds on C. macrocarpa, and strengthens the recommendation to remove diseased plant material early, to maintain a low level of natural-spore inoculum within stands. It also indicates that pruning during wet weather should be avoided. Cleaning or disinfecting implements among trees may also be appropriate when conducting silvicultural operations in diseased plantations.

Susceptibility of Grapevine Pruning Wounds and Symptom Development in Response to Infection by Phaeoacremonium aleophilum and Phaeomoniella chlamydospora.

Fresh to 10-month-old pruning wounds on grapevine cvs. Thompson Seedless and Cabernet Sauvignon were inoculated with Phaeoacremonium aleophilum or Phaeomoniella chlamydospora at approximately 1 × 106 spores/ml. Successful infection was determined by isolation of the pathogen from necrotic margins of cankers or from vascular discoloration assessed 4 months after each inoculation date. Disease incidence decreased as the length of time between pruning and inoculation increased; however, wounds remained susceptible for up to 4 months. Vascular discoloration was significantly less extensive in the noninoculated control than in inoculated spurs. Reduction of shoot length in both cultivars varied depending on pruning wound age at the time of inoculation. In a separate study, inoculation of fresh pruning wounds of Cabernet Sauvignon resulted in successful infection regardless of the time of pruning from February to December.

Protection of grapevine pruning wounds from infection byEutypa latausingTrichoderma harzianumandFusarium lateritium

Trichoderma harzianum applied to grapevine pruning wounds in a spore suspension and in the commercial formulations of Trichoseal, Trichoseal spray and Vinevax pruning wound dressing reduced recovery of Eutypa lata in the glasshouse and in the field. Recovery of E. lata was significantly reduced (P < 0.001) when fresh wounds were treated with viable T. harzianum 2 or 7 days before inoculation with ascospores of the pathogen in the glasshouse. In field experiments, recovery of E. lata was significantly reduced (P < 0.001) when fresh pruning wounds were treated with spores of T. harzianum, Fusarium lateritium or Vinevax 1 or 14 days before ascospores were applied. In general, a delay of 14 days between wounding and inoculation with ascospores of E. lata reduced recovery of the pathogen compared with inoculation on the day after wounding.

An Evaluation of Four Glyphosate Formulations on Dormant Conifers

In 1995, Monsanto Chemical Co. announced that they would replace Roundup herbicide with Roundup Pro for use in the ornamentals and turf markets. Both products contain 4 lb a.i./gal glyphosate, but Roundup Pro contains a more-active surfactant. Though Roundup was labeled as a nonselective herbicide, dormant conifers were found to have varying degrees of resistance to it. Directed sprays that hit the lower two-thirds of many dormant conifers became common practice in the industry. Because the surfactant in Roundup Pro increases the activity of the glyphosate, a series of trials were initiated in 1996 in Connecticut, Pennsylvania, and Vermont in which four glyphosate formulations were applied to a variety of dormant conifers. Roundup, Roundup Pro, Glyfos, and Accord (with and without surfactant) were applied either over-the-top or as directed sprays to the lower 18 inches of the plants at rates between 0.5 and 3 lb a.i./acre. Plants treated included globe arborvitae; upright yew; Canadian hemlock; Colorado, Norway and white spruce; Douglas fir; eastern white pine; and balsam, Canaan, and Fraser fir. In a preliminary study, injury to the spruces in the form of dwarfed and chlorotic new growth was primarily associated with fresh pruning wounds. Accord plus surfactant and Roundup Pro injured more spruces than Roundup, but injury was slight. No injury was observed in upright yew with any formulation at rates up to 0.75 lb a.i./acre. Injury to arborvitae was greatest with Accord plus surfactant, intermediate with Roundup Pro, and least with Roundup. Results are inconclusive at this time, but the results of additional studies available early in the next growing season.will be presented.

Response of the Bronze Birch Borer to Pruning Wounds on Paper Birch

Healthy appearing paper birch trees were pruned at the beginning of the bronze birch borer's emergence period. Some wounds were left exposed while others were treated with a commercial wound dressing. Bronze birch borer adults, particularly females, were attracted to fresh pruning wounds on paper birch. Treating the pruning wounds with a wound dressing did not reduce the wound's attractiveness to the borers.

Protection of Grapevine Pruning Wounds from Infection byEutypa Armeniacaein New York State

Benomyl at 10 mg/mL, applied as a paint to fresh pruning wounds, provided 84%, 93%, and 100% control of infection by <i>Eutypa armeniacae</i> in Concord, Catawba and Aurore grapevines, respectively. This fungicide provides an effective and economical control of Eutypa dieback in New York State.