Autumnapplied urea and other compounds to suppress &lt;i&gt;Venturia inaequalis&lt;/i&gt; ascospore production

Beresford, R.; Horner, I.J.; Wood, P.N.

doi:10.30843/nzpp.2000.53.3614

Cited by 10 publications

(12 citation statements)

References 5 publications

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“…The differences in numbers of ascospores trapped at the two experimental sites were probably due to the different climates at the two sites, since the periodicity of rainfall causes differences in ascospore maturation and release (MacHardy 1996). The significant effect of the nutrient amendment urea, which caused a 77% reduction overall in ascospore numbers in this trial, agreed with those from other field trials, in which urea reduced ascospore numbers by 65-95% in England (Burchill 1968) and 88% in New Zealand (Beresford et al 2000). However, Bio-Start™ was ineffective despite the leaf decomposition effects described in recent European trials (G. Besamusca, pers.…”

Section: Discussionsupporting

confidence: 89%

“…Application of nitrogenous compounds has also been found to reduce primary inoculum of apple black spot. Many authors have reported the beneficial effects of autumn applications of urea (Burchill 1968;Carisse et al 2000;Beresford et al 2000). Ross & Hamlin (1965) reported that nitrate and ammonium salts, and amino acids were equally effective to urea, completely preventing development of pseudothecia.…”

Section: Introductionmentioning

confidence: 99%

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Treatment of overwintering apple leaves to reduce primary inoculum of apple black spot

Tshomo¹,

Horner²,

Walter³

et al. 2003

NZPP

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Field trials were conducted in Hawke's Bay and Lincoln into methods of treating over-wintering apple leaves to reduce ascospore production by the apple black spot pathogen, Venturia inaequalis. The leaf treatments comprised three levels of nutrient amendments (including a water control) and five levels of saprophytic fungal isolates (including a nofungus control), in a factorial design. Leaves were left to over-winter on the orchard floor, and in spring the V. inaequalis ascospores released were trapped on glass slides and counted. Ascospore numbers were reduced (P<0.05) by the leaf amendment urea, which alone caused 73% reduction, but not by the Bio-Start™ product. The effect of fungal isolates was not significant (P=0.12), although when combined with the water treatment, the isolates, Chaetomium, Phoma and Epicoccum spp. and Trametes versicolor reduced numbers of ascospores by 33, 27, 15 and 28%, respectively, compared to the no-fungus control. When combined with urea, the Chaetomium isolate reduced ascospore numbers by 92 and 82% compared to the nil fungus/water control treatments in Hawke's Bay and Lincoln, respectively, indicating that this treatment has potential for reducing primary inoculum of apple black spot.

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Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Treatment of overwintering apple leaves to reduce primary inoculum of apple black spot

Tshomo¹,

Horner²,

Walter³

et al. 2003

NZPP

Self Cite

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“…In relation to black spot control, the higher the autumn urea application rate, the greater the suppression of ascospore production (Beresford et al 2000). However, application rates of 2-5% urea, which in these studies were shown to avoid bud damage, can still give substantial ascospore suppression and are therefore useful for black spot management.…”

Section: Discussionmentioning

confidence: 86%

“…Urea applied to apple trees during leaf fall suppresses the production of ascospores of the black spot fungus (Venturia inaequalis) the following spring and is an important component in the management of black spot in New Zealand apple orchards (Beresford et al 2000). The closer to leaf fall that urea is applied, the more effective the suppression of ascospore production, and therefore 2-3 urea applications are often made during leaf fall.…”

Section: Introductionmentioning

confidence: 99%

Avoiding apple bud damage from autumnapplied urea for black spot (<i>Venturia inaequalis</i>) control

Wood¹,

Beresford²

2000

NZPP

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Three field trials in Hawke's Bay and Pukekohe, which involved the apple cvs Braeburn, Royal Gala, Fuji and Granny Smith, showed that urea applied to trees in autumn for black spot (Venturia inaequalis) control at concentrations >5% was associated with death of apple buds the following spring. Urea containing 0.9% biuret caused significantly more bud death than urea with 0.35% biuret, but the toxicity of biuret appeared to be unimportant compared to the toxicity of the urea itself, when urea was applied at concentrations >5%. There was no cumulative bud damage between seasons when urea was applied at 5% in four successive autumns. Multiple applications of urea in a single autumn caused bud death and it appeared that the total amount of urea applied in one year should not exceed 100 kg/ha (equivalent to one application of 5% urea).

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“…Many growers are using postharvest foliar urea applications as a way to ensure that bud reserves of N are high, even when added fertilizer N is being reduced with the goal of increasing crop quality (Sánchez et al, 1995). There is also some evidence that a postharvest urea application increases leaf decay rates and reduces the incidence of disease the following year (Beresford et al, 2000;Burchill, 1968). It is important to determine whether B can be added effectively to a postharvest foliar urea application, thus eliminating the need for a B application the following spring.…”

Section: Methodsmentioning

confidence: 99%

Effect of Postharvest Soil and Foliar Application of Boron Fertilizer on the Partitioning of Boron in Apple Trees

Sánchez¹,

Righetti²

2005

HortSci

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This study was carried out on mature 'Delicious' apple trees (Malus domestica Borkh.) on EM 9 rootstock. Labeled B (99.63 Atom % 10 B) was applied as boric acid. Treatments were postharvest foliar B at 375 mg·L -1 , postharvest foliar B (375 mg·L -1 ) plus urea (2.5% wt/vol), and a soil application at the same per-tree rate as the foliar treatments (16 g boric acid/tree). Postharvest foliar B applied with or without urea was effi ciently transported from the leaves into storage tissues for the next year´s growth. However, soil-applied B remained mostly in the roots while very little was translocated to the above-ground portions of the tree at full bloom. When urea was added to a foliar B spray, the amount of B in the roots and fl ower clusters increased at full bloom. Although increasing the effi ciency of foliar B applications may not be necessary, combining urea and B into a single application is recommended when growers want to apply both N and B. Shoot leaves from all treatments collected late in the season (midsummer) had similar B concentrations, even though treatments altered the amount of added B that was present in different tree tissues early in the season.

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Autumnapplied urea and other compounds to suppress <i>Venturia inaequalis</i> ascospore production

Cited by 10 publications

References 5 publications

Treatment of overwintering apple leaves to reduce primary inoculum of apple black spot

Treatment of overwintering apple leaves to reduce primary inoculum of apple black spot

Avoiding apple bud damage from autumnapplied urea for black spot (<i>Venturia inaequalis</i>) control

Effect of Postharvest Soil and Foliar Application of Boron Fertilizer on the Partitioning of Boron in Apple Trees

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