scholarly journals The effect of Regalis® (prohexadione calcium) on the reduction of fire blight (Erwinia amylovora) severity in apple trees

2004 ◽  
Vol 10 (2) ◽  
Author(s):  
P. Sobiczewski ◽  
T. Bubán
Keyword(s):  
Active Ingredient ◽  
Fire Blight ◽  
Shoot Growth ◽  
Control Strategies ◽  
Fruit Trees ◽  
Pome Fruit ◽  
Apple Trees ◽  
Obvious Effect ◽  
One Year ◽  
Prohexadione Calcium

Due to the lack of effective and non-phytotoxic materials for control of the blossom and shoot blight phase of fire blight in pome fruit trees, two novel control strategies have emerged: shoot growth retardation by bioregulators and applying resistance inducer compounds. Prohexadione calcium (ProCa) is the active ingredient of the bioregulator Regalis® registered in several European countries. The reduction of shoot growth elongation is the most obvious effect of ProCa. Furthermore, it causes significant changes in the spectrum of flavonoids and their phenolic precursors, leading to the considerable reduction of susceptibility to fire blight. In Poland, potted one-year-old apple trees of cvs. Gala Must grafted on M.26 and Sampion on M.9 (in 2001) as well as Gala Must on P.60 (in 2002) were treated with Regalis® at a range of concentration of 250, 150 or 150 + 100 ppm, respectively. The inoculation of shoots was made with the strain No.691 of E. amylovora (107 cfu/ml), on the 7th and 21st'day after treatments with Regalis. In Hungary, during the years of 2002 and 2003 one-year-old container grown apple trees of the cvs. Idared/M.9 and Freedom/M.9 were treated with the prohexadione-Ca, the active ingredient of Regalis® 100, 150 or 200 ppm, two weeks before inoculation with the Ea 1 strain of E. amylovora (107 cfu/m1). In Poland, the suppression of fire blight in shoots reached up to 80%, depending on concentration and application time of Regalis®. In Hungary, the effect of prohexadione-Ca treatments, determined by the length of necrotic lesion developed, proved to be better than that of streptomycin used for comparison.

scholarly journals Effect of Prohexadione-Calcium Dose Level on Shoot Growth and Fire Blight in Young Apple Trees

Plant Disease ◽  
2004 ◽  
Vol 88 (10) ◽  
pp. 1099-1106 ◽  
Author(s):  
J. L. Norelli ◽  
S. S. Miller
Keyword(s):  
Fire Blight ◽  
Shoot Growth ◽  
High Dose ◽  
Apple Orchards ◽  
Calcium Treatment ◽  
Apple Trees ◽  
Resistance Response ◽  
Treatment Dose ◽  
Prohexadione Calcium ◽  
Young Apple

Prohexadione-calcium suppresses both shoot growth and fire blight in apple. In young apple orchards, there are conflicting requirements to control fire blight and allow sufficient tree growth for tree establishment. Application of prohexadione-calcium to various cultivars of orchard-grown apple trees ranging in age from newly planted to fifth-leaf trees indicated that fewer high-dose (125 or 250 mg ·liter-1) applications of prohexadione-calcium provided a better balance between fire blight control and growth in young orchards than multiple low-dose (30 or 63 mg·liter-1) applications. The response of early-season shoot growth to prohexadione-calcium treatment dose was linear. However, trees that received high doses of prohexadione-calcium tended to grow more in the latter part of the season, resulting in little or no difference in total seasonal growth between trees that received a few high or multiple low doses of prohexadione-calcium. Enhancement of fire blight resistance by prohexadione-calcium was correlated with shoot growth suppression at the time of inoculation, and the resistance response to prohexadione-calcium treatment dose was linear. Fire blight management strategies that use prohexadione-calcium in young apple orchards are discussed.

Herbicide Effects on Weed Control and Shoot Growth of Young Apple (Malus sylvestris) and Peach (Prunus persica) Trees

1994 ◽  
Vol 8 (4) ◽  
pp. 840-848 ◽  
Author(s):  
Chester L. Foy ◽  
Susan B. Harrison ◽  
Harold L. Witt
Keyword(s):  
Shoot Growth ◽  
Field Experiments ◽  
Prunus Persica ◽  
Weed Species ◽  
Apple Trees ◽  
Herbicide Treatments ◽  
One Year ◽  
Broadleaf Species ◽  
Old Trees ◽  
Peach Trees

Field experiments were conducted at two locations in Virginia to evaluate the following herbicides: alachlor, diphenamid, diuron, metolachlor, napropamide, norflurazon, oryzalin, oxyfluorfen, paraquat, pendimethalin, and simazine. One experiment involved newly-transplanted apple trees; the others, three in apple and one in peach trees, involved one-year-old trees. Treatments were applied in the spring (mid-April to early-May). Control of annual weed species was excellent with several treatments. A broader spectrum of weeds was controlled in several instances when the preemergence herbicides were used in combinations. Perennial species, particularly broadleaf species and johnsongrass, were released when annual species were suppressed by the herbicides. A rye cover crop in nontreated plots suppressed the growth of weeds. New shoot growth of newly-transplanted apple trees was increased with 3 of 20 herbicide treatments and scion circumference was increased with 11 of 20 herbicide treatments compared to the nontreated control. Growth of one-year-old apple trees was not affected. Scion circumference of one-year-old peach trees was increased with 25 of 33 herbicide treatments.

Response of newly planted peach and apple trees to superphosphate

1975 ◽  
Vol 26 (3) ◽  
pp. 521 ◽  
Author(s):  
BK Taylor
Keyword(s):  
Tree Growth ◽  
Phosphate Fertilizer ◽  
Fruit Trees ◽  
Yield Response ◽  
Apple Trees ◽  
Leaf Analysis ◽  
Major Interest ◽  
Marked Decline ◽  
One Year ◽  
Peach Trees

The response of peach and apple trees to added superphosphate was recorded both in the nursery and later in the orchard after transplanting. The peach and apple trees responded positively to phosphate applications in both the nursery and the orchard despite the initial presence of medium to high phosphate levels in the soils. Of major interest, too, was the absence of a consistent interaction between the phosphate treatments applied in the separate years. This suggested that the trees could not accumulate enough phosphorus in any one year to influence their response to further phosphate. Leaf analysis showed two important effects in relation to the phosphate treatments. Firstly, since high rates of application of fertilizer led to only small increases in the levels of phosphorus in the leaves, tree growth rate and phosphate absorption rate are apparently closely coupled. Secondly, the deliberate withholding of phosphate fertilizer from all trees in the fourth season led to a marked decline in the levels of phosphorus in the leaves of both peach and apple, which suggested that phosphate fertilizer should be applied annually to young fruit trees. With apple, but not peach, increasing the rate of phosphate applied in the third season stimulated the number of flower buds initiated, but this effect was not simply the result of increased vegetative growth. On the other hand, phosphate application to the peach trees in the orchard resulted in a positive fruit set and yield response in the absence of any tree growth response.

scholarly journals CRISPR genotyping as complementary tool for epidemiological surveillance of Erwinia amylovora outbreaks

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250280
Author(s):  
Rafael J. Mendes ◽  
João Pedro Luz ◽  
Conceição Santos ◽  
Fernando Tavares
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Blot Hybridization ◽  
Fruit Trees ◽  
Epidemiological Surveillance ◽  
Economic Losses ◽  
Pome Fruit ◽  
Dot Blot ◽  
Virulence Markers ◽  
Clonal Population Structure

Fire blight is a destructive plant disease caused by Erwinia amylovora affecting pome fruit trees, and responsible for large yield declines, long phytosanitary confinements, and high economic losses. In Portugal, the first major fire blight outbreaks occurred in 2010 and 2011, and although later considered eradicated, the emergence of other outbreaks in recent years stressed the need to characterize the E. amylovora populations associated with these outbreaks. In this regard, CRISPR genotyping, assessment of three virulence markers, and semi-quantitative virulence bioassays, were carried out to determine the genotype, and assess the virulence of thirty-six E. amylovora isolates associated with outbreaks occurring between 2010 and 2017 and affecting apple and pear orchards located in the country central-west, known as the main producing region of pome fruits in Portugal. The data gathered reveal that 35 E. amylovora isolates belong to one of the widely-distributed CRISPR genotypes (5-24-38 / D-a-α) regardless the host species, year and region. Ea 680 was the single isolate revealing a new CRISPR genotype due to a novel CR2 spacer located closer to the leader sequence and therefore thought to be recently acquired. Regarding pathogenicity, although dot-blot hybridization assays showed the presence of key virulence factors, namely hrpL (T3SS), hrpN (T3E) and amsG from the amylovoran biosynthesis operon in all E. amylovora isolates studied, pathogenicity bioassays on immature pear slices allowed to distinguish four virulence levels, with most of the isolates revealing an intermediate to severe virulence phenotype. Regardless the clonal population structure of the E. amylovora associated to the outbreaks occurring in Portugal between 2010 and 2017, the different virulence phenotypes, suggests that E. amylovora may have been introduced at different instances into the country. This is the first study regarding E. amylovora in Portugal, and it discloses a novel CRISPR genotype for this bacterium.

scholarly journals COMPARATIVE STUDIES ON NEWLY DEVISED AND CONVENTIONAL METHODS OF GRAFTING IN ONE-YEAR-OLD `FUJI' APPLE TREES/ M.2 /MALUS PRUN1FOLIA SEEDLINGS.

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 691b-691
Author(s):  
Yong-Koc Kim ◽  
Yong-Suk Kim
Keyword(s):  
Comparative Studies ◽  
Shoot Growth ◽  
Growing Season ◽  
Complete Healing ◽  
Apple Trees ◽  
Tree Form ◽  
Xylem Tissue ◽  
Fuji Apple ◽  
Conventional Methods ◽  
One Year

Experiments were carried out to evaluate some newly devised and conventional methods of grafting using `Fuji' apple trees on M.26/M. prunifolia rootstocks. Out of various methods of grafting, the modified inverted-veneer grafting and the inverted bark grafting showed a complete healing of the grafting union leaving no part of xylem tissue exposed in the air. However, owing to the longer period of growth for the trees grafted by the modified inverted-veneer grafting than the inverted bark grafting during the period of one growing season, the modified inverted-veneer gave slightly better shoot growth than the inverted bark grafting. It was clear that the former two methods were superior to the all other grafting methods, i.e., whip-and-tongue grafting, modified veneer grafting, inverted-veneer grafting, bark grafting, and chip budding in the grafting union healing, shoot growth, and tree form performance.

scholarly journals The Effect of Prohexadione-calcium on Fruit Set and Chemical Thinning of Apple Trees

HortScience ◽  
2007 ◽  
Vol 42 (6) ◽  
pp. 1361-1365 ◽  
Author(s):  
Duane W. Greene
Keyword(s):  
Vegetative Growth ◽  
Fire Blight ◽  
Fruit Set ◽  
Fruit Size ◽  
Load Level ◽  
Apple Trees ◽  
Management Tools ◽  
Crop Load ◽  
Prohexadione Calcium ◽  
Treated Apple

Prohexadione-calcium (ProCa) has emerged as one of the most important management tools that an orchardist has available to control vegetative growth and to reduce the incidence and severity of fire blight. It has also been implicated in increased fruit set on treated apple trees. This investigation was initiated to confirm the effects of ProCa on fruit set and to evaluate different thinning strategies that might be used to appropriately thin treated trees. ProCa increased fruit set when applied at petal fall at initial rates of 125 or 250 mg·L−1 in three of the four experiments described in this article. Thinners were applied before, at the time of, and after application of ProCa. In all experiments, chemical thinners did not reduce fruit set to the same crop load level on ProCa-treated trees as they did on untreated trees. It was concluded that a different and more aggressive chemical thinning strategy must be used on trees that were treated with ProCa. Fruit size was reduced on ProCa-treated trees. This reduction was usually, but not always, related to increased fruit set. ProCa increased the number of pygmy fruit on ‘Delicious’ apple trees.

scholarly journals Management of Fire Blight Using Pre-bloom Application of Prohexadione-Calcium

Plant Disease ◽  
2020 ◽  
Vol 104 (4) ◽  
pp. 1048-1054
Author(s):  
Anna E. Wallis ◽  
Kerik D. Cox
Keyword(s):  
New York ◽  
Tree Growth ◽  
Cell Walls ◽  
Fire Blight ◽  
Shoot Growth ◽  
New York State ◽  
Bacterial Disease ◽  
Cortical Parenchyma ◽  
Shoot Blight ◽  
Prohexadione Calcium

Fire blight, a bacterial disease of rosaceous plants caused by Erwinia amylovora, is one of the most important diseases affecting commercial apple production worldwide. Antibiotics, applied at bloom to protect against blossom infection, are the most effective means of management but raise concern due to the potential for antibiotic resistance in both the pathogen population and nontarget organisms. In addition, most fire blight outbreaks in New York State often emerge in late June to July as shoot blight, calling into question the role of blossom infections and the antibiotic applications made to manage them. Prohexadione-calcium (PhCa) is a gibberellic acid inhibitor used post-bloom to control shoot vigor and to manage shoot blight. However, the magnitude of shoot blight management is directly related to the suppression of shoot growth, which is undesirable, especially in young orchards during establishment years. PhCa is believed to control shoot blight by thickening cell walls in cortical parenchyma, preventing invasion of host tissues by E. amylovora. We hypothesize that PhCa applied pre-bloom could similarly prevent invasion of blossom pedicels following infection, leading to reduced disease incidence. We evaluated novel pre-bloom PhCa programs for their effects on disease management (blossom and shoot blight) as well as their impact on shoot growth for three years in a mature ‘Gala’ orchard in New York. In all three years of the study, all PhCa programs resulted in less than 27% incidence (71% control) of blossom blight and less than 13% incidence (77% control) of shoot blight with minimal effect on tree growth. Inclusion of a biopesticide during bloom further reduced the incidence of blossom blight in one year of three. Using light microscopy, we found that cell walls in the cortical parenchyma of fruitlet pedicels on trees receiving pre-bloom PhCa applications were significantly thicker than those of untreated trees 40 days after full bloom and inoculation. Overall, we found that pre-bloom applications of PhCa had utility in reducing blossom blight and shoot blight with minimal impacts on tree growth. These pre-bloom programs would fit with standard production practices and may contribute toward the development of fire blight management programs without the use of antibiotics.

Managing Vegetative Growth of Apples with Prohexadione Calcium can Influence Mid-season Spray Coverage

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 451f-452
Author(s):  
J.R. Evans ◽  
J.A. Balles ◽  
L.H. Bennett ◽  
B.A. Brinkman ◽  
A.H. Harrell ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Plant Growth Regulator ◽  
Shoot Growth ◽  
Crop Protection ◽  
Shoot Length ◽  
Tree Canopy ◽  
Apple Trees ◽  
Air Blast ◽  
Previously Treated ◽  
Prohexadione Calcium

Prohexadione calcium (BAS 125W or Apogee™) is a plant growth regulator being developed to control vegetative growth in apples. Prohexadione calcium acts within a plant by blocking the biosynthesis of growth-active gibberellin. The result is decreased cell elongation; thus, reduced shoot length. Applications of prohexadione calcium beginning when the apple trees have 2 to 15 cm of new shoot growth significantly reduce seasonal vegetative growth. Mid-season measurements of air blast spray coverage using water-sensitive cards show that trees previously treated with prohexadione calcium have greater spray coverage within the tree canopy than untreated trees. Hence, more efficient crop protection can be expected in apple trees treated with prohexadione calcium.

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