Fertiliser practice and yield losses in process potato crops grown in Canterbury, New Zealand

Dieback and crown rot affect about 18 of blueberry plants in the main New Zealand production areas costing about 500000 annually due to yield losses and replanting costs Samples of symptomatic plants and stems were collected from six blueberry farms in the central North Island to determine which pathogens were responsible From the 70 plants collected numerous isolations from branch bases and tips stem lesions and crowns revealed the apparent presence of Botryosphaeria species in 69 645 543 and 70 of samples respectively These Botryosphaeria spp were also found in a few roots and leaves but not fruit from symptomatic plants nor in healthy asymptomatic stems Morphological examination of conidia from 40 cultures identified B lutea B parva B lutea/australis and B obtusa with one unidentified Botryosphaeria species apparently of the Neofusicoccum type Molecular identification of 14 representative isolates from these 40 confirmed the presence of B lutea B parva and B australis

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First Report of Potato spindle tuber viroid in Tomato in New Zealand

Plant Disease ◽

10.1094/pdis.2001.85.9.1027b ◽

2001 ◽

Vol 85 (9) ◽

pp. 1027-1027 ◽

Cited By ~ 17

Author(s):

D. R. Elliott ◽

B. J. R. Alexander ◽

T. E. Smales ◽

Z. Tang ◽

G. R. G. Clover

Keyword(s):

Electron Microscopy ◽

Polymerase Chain Reaction ◽

New Zealand ◽

Plant Protection ◽

Potato Spindle Tuber Viroid ◽

Mechanical Transmission ◽

Chain Reaction ◽

Polymerase Chain ◽

Plant Pathol ◽

Potato Crops

During May 2000, symptoms resembling those of Potato spindle tuber viroid (PSTVd) infection were observed in glasshouse tomatoes (cv. Daniella) growing on one site in Tuakau, South Auckland, New Zealand. Symptoms appeared 2 to 3 months after planting, were confined to plant tops, and included leaf interveinal chlorosis, epinasty, and brittleness. Affected plants comprised ≍10% of the crop and were located near access points. PSTVd was identified in symptomatic plants by the Dutch Plant Protection Service and confirmed by mechanical transmission and grafting to tomato cv. Rutgers and reverse transcription polymerase chain reaction (2). The sequenced genome of this isolate (Accession AF369530) was 358 nt in length and had the closest homology to a Dutch isolate (Accession X17268). Electron microscopy did not reveal the presence of any viruses in affected plants and specific tests for other tomato pathogens were negative. A survey of 50 tomato glasshouse facilities throughout New Zealand revealed three further infected sites, two located close to the original site and one in Nelson, some 480 km distant. However, a survey of field-grown potato crops within 1.5 km of the original outbreak site did not reveal the presence of the viroid. PSTVd is seed transmitted and was probably introduced in glasshouses by use of infected seed. Glasshouse tomatoes are an important crop in New Zealand and annual production is currently 40,000 tonnes. The yield of affected plants may be decreased by up to 80% if suitable controls are not implemented (1). References: (1) S. Kryczynski et al. Phytopath. Polonica 22:85, 1995. (2) A. M. Shamloul et al. Can. J. Plant Pathol. 19:89, 1997.

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The southern ladybird (Cleobora mellyi) as a new species association biocontrol agent of tomatopotato psyllid (Bactericera cockerelli)

New Zealand Plant Protection ◽

10.30843/nzpp.2014.67.5783 ◽

2014 ◽

Vol 67 ◽

pp. 321-321

Author(s):

A.R. Pugh ◽

D.M. O'Connell ◽

S.D. Wratten

Keyword(s):

New Zealand ◽

Biocontrol Agent ◽

Green Peach Aphid ◽

Generalist Predator ◽

Bactericera Cockerelli ◽

Potato Tubers ◽

Greenhouse Whitefly ◽

Potato Aphid ◽

Floral Resource ◽

Potato Crops

Since its discovery in New Zealand in 2006 the tomatopotato psyllid (Bactericera cockerelli) (TPP) has emerged as a major pest of solanaceous crops In potato crops the management of TPP has predominantly relied on insecticide applications as biological control by generalist predators has been constrained by both insecticide use and temporal and spatial scales This research sought to further investigate a generalist predator already established in New Zealand the southern ladybird (Cleobora mellyi) introduced from Tasmania as a biocontrol agent for Paropsis charybdis in the 1970s and 1980s as a potential biocontrol agent of TPP The southern ladybirds prey selection ladybird longevity and ladybirdTPP predatorprey dynamics were investigated A choice test assay utilised small experimental arenas of three alternative choices between (1) TPP and green peach aphid Myzus persicae (2) TPP and potato aphid Macrosiphum euphorbiae and (3) TPP and greenhouse whitefly Trialeurodes vaporariorum Cleobora mellyi larvae and adults did not demonstrate a significant prey preference between TPP and either green peach aphid or potato aphid but did show a significant aversion to greenhouse whitefly Longevity trials consisted of a water only control and three treatments (1) a floral resource (flowering buckwheat) (2) 10 TPP/day or (3) flowering buckwheat 10 TPP/day All three treatments lived significantly longer than the water only control and southern ladybirds adults lived significantly longer when given both the floral resource and TPP compared to only being given TPP A glasshouse mesocosm study was used to investigate ladybirdTPP predatorprey dynamics Within 3 weeks the southern ladybird had significantly reduced TPP densities in the treatment in which they were present along with potato plants and TPP compared to the treatment without ladybirds a reduction that was maintained until the completion of the experiment Where there was only TPP and no ladybird no potato tubers were formed; in the presence of southern ladybird small and few potato tubers were formed while the most tubers were produced in insectfree controls This indicates a specieslevel trophic cascade This study has shown that the southern ladybird is capable of predating upon TPP and reducing densities within the controlled conditions of a glasshouse However with the current state of knowledge the southern ladybird is not likely to be a viable predator for controlling TPP in potato crops outside glasshouses in New Zealand This is due in part to the freedom to disperse in the field the economics of such large scale rearing and fundamental differences in habitat type compared to their natural environment but applications in alternative contexts cannot be ruled out

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The effect ofSitona discoideusGyllenhal (Coleoptera: Curculionidae) on lucerne yields in New Zealand

Bulletin of Entomological Research ◽

10.1017/s000748530001453x ◽

1985 ◽

Vol 75 (3) ◽

pp. 429-442 ◽

Cited By ~ 24

Author(s):

S. L. Goldson ◽

C. B. Dyson ◽

J. R. Proffitt ◽

E. R. Frampton ◽

J. A. Logan

Keyword(s):

New Zealand ◽

Dry Matter ◽

Larval Density ◽

Yield Response ◽

Severe Drought ◽

Yield Losses ◽

Wet Season ◽

Larval Population ◽

Adult Feeding ◽

The Impact

AbstractThe impact of injury by larvae and adults ofSitona discoideusGyllenhal on lucerne production was studied in two consecutive seasons at two adjacent sites near Christchurch, New Zealand. The root-feeding larvae were found to be more damaging than the adults; in the first cut in the 1982–83 season in a three-year-old stand, larvae reduced dry matter yield by 18%. In the wetter following season in a one-year-old stand, second and third cut losses of 43 and 30% dry matter production, respectively, were recorded. In both seasons, the lucerne had apparently substantially recovered from larval damage by the time of the last cuts. In the drier 1982–83 season, two cuts were taken compared with four in the 1983–84 season. Adult feeding was found to reduce second cut wet yields by 20–30% in the 1982–83 season but had no measurable effect in the 1983–84 season. In both seasons, manipulated ranges of larval densities showed that damage appeared only when larval populations were in excess of a distinct larval population density threshold. At larval densities less than this threshold, yield was unaffected; above the threshold, yield losses were independent of larval density. Such a yield response curve was found to be adequately described mathematically by a simple arctan model; this approach allowed the threshold to be further defined and overall estimates to be made of the yield losses arising from larval damage. The threshold occurred at about 1200 larvae/m2in the dry season and about 2100 larvae/m2in the wet season. This suggested moisture sensitivity and the possibility that the crop may enter a damage-induced dormancy related to that observed during a severe drought.

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The application of 980 degree days as a trigger for rapid increases in Bactericera cockerelli in Hawkes Bay solanaceae crops

New Zealand Plant Protection ◽

10.30843/nzpp.2015.68.5845 ◽

2015 ◽

Vol 68 ◽

pp. 441-441

Author(s):

N.M. Taylor ◽

R.C. Butler ◽

J. Vereijssen

Keyword(s):

Host Plants ◽

Sticky Trap ◽

Potato Psyllid ◽

Bactericera Cockerelli ◽

Yield Losses ◽

Degree Days ◽

Plant Monitoring ◽

Trap Catches ◽

Potato Crops

During 200708 the tomato potato psyllid (TPP Bactericera cockerelli) was observed in outdoor tomato and potato crops in Hawkes Bay Many crops were heavily infested resulting in severe yield losses and in some cases crop abandonment Since then growers have been proactive in plant monitoring and sticky trap use but these methods are expensive and quite often a calendar spray programme is begun once the first adult TPP have been observed in traps It has been proposed that 980 degreedays (DDs) from 1 July is used as an indicator of when TPP numbers are about to increase rapidly in North Island crops This study describes the application of 980 DDs to recent sticky trap data from Hawkes Bay For most sites 980 DDs occurred just before rapid increases in adult TPP numbers However there were a small number of sites where this was not so The presence of noncrop TPP host plants bordering these sites may explain rapid increases in TPP trap catches well before reaching 980 DDs

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Towards universal detection of Luteoviridae

New Zealand Plant Protection ◽

10.30843/nzpp.2009.62.4855 ◽

2009 ◽

Vol 62 ◽

pp. 407-407

Author(s):

A. Chomic ◽

M.N. Pearson ◽

K.F. Armstrong

Keyword(s):

New Zealand ◽

Plant Virus ◽

Universal Primers ◽

High Homology ◽

Yield Losses ◽

Virus Family ◽

Low Concentration ◽

Conserved Regions ◽

Universal Detection ◽

Pcr Conditions

Luteoviridae is a plant virus family of 26 species which causes yield losses in cereals potatoes and other economically important crops worldwide Accurate detection is an important component of controlling the spread of luteoviruses and reducing yield losses PCRbased detection is often the method of choice for Luteoviridae as it is more sensitive than serological methods which frequently fail to detect infection due to the low concentration of luteoviruses in plants Since the currently available luteovirus primers are mostly speciesspecific and work under different PCR conditions universal primers are desirable Seven primers were tested that were designed to target the most conserved regions of the Luteoviridae genomes and that possess high homology to over 75 of Luteoviridae species Thirty luteovirus isolates representing 15 species were obtained from New Zealand and overseas these included all five species from the Luteovirus genus eight of the nine species from the Polerovirus genus (except CYDV RPS) PEMV1 (the only species from the Enamovirus genus) and CtRLV (which is not assigned to a genus) Between them the three combinations of primers detected all 13 of the Luteovirus and Polerovirus species tested

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The control of tan spot of wheat (caused by Pyrenophora triticirepentis a possible emerging disease in New Zealand

New Zealand Plant Protection ◽

10.30843/nzpp.2015.68.5823 ◽

2015 ◽

Vol 68 ◽

pp. 428-433

Author(s):

I.C. Harvey ◽

R.A. Craigie ◽

B.L. McCloy

Keyword(s):

Life Cycle ◽

New Zealand ◽

Grain Yield ◽

Tan Spot ◽

Green Leaf ◽

Wheat Seed ◽

Yield Losses ◽

Essential Step ◽

Small Plot ◽

Set Up

Pyrenophora triticirepentis the cause of tan spot of wheat was first recorded in New Zealand in 1979 but only on wheat seed However this pathogen has recently been recorded as causing possible yield losses in isolated crops A small plot trial set up in a central Canterbury crop of cv Saracen tested several fungicides alone or in mixtures Control was not entirely effective since tan spot infection was well established when the first applications were made at GS33 (third node detectible) Nevertheless two triazoles (propiconazole and prothioconazole) and three SDHI fungicides (isopyrazam bixafen plus prothioconazole and fluxapyroxad plus epoxiconazole) all gave similar levels of control either when applied alone or in mixtures Two triazoles (epoxiconazole and difenoconazole) were less effective alone while addition of strobilurin (pyraclostrobin) to mixtures gave little extra control Several treatments showed significant increases in green leaf retention and final grain yield The life cycle of the pathogen dictates that management of the overwintering inoculum in stubble is a probable essential step in control of the disease

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Effect of Colletotrichum coccodes on Potato Yield, Tuber Quality, and Stem Colonization During Spring and Autumn

Plant Disease ◽

10.1094/pdis.1999.83.6.561 ◽

1999 ◽

Vol 83 (6) ◽

pp. 561-565 ◽

Cited By ~ 42

Author(s):

Leah Tsror (Lahkim) ◽

Orly Erlich ◽

Marina Hazanovsky

Keyword(s):

Vascular Tissue ◽

Potato Yield ◽

Potato Cultivars ◽

Colletotrichum Coccodes ◽

Tuber Quality ◽

Yield Losses ◽

Inoculation Methods ◽

Significant Yield ◽

Potato Crops

The response of five potato cultivars to Colletotrichum coccodes was tested in artificially inoculated fields for three consecutive spring and autumn seasons during 1994 to 1996. Significant yield reductions (22 to 30%) were observed in all tested cultivars. Results varied between years, but yield losses were more severe in autumn than in spring. Stem infections of plants were observed 90 days after planting on the surface of the stem and in vascular tissue. C. coccodes inoculation also resulted in reduction of the quality of daughter tubers. Cultivars Cara and Nicola were found to be less susceptible to tuber infection than Alpha, Desiree, and Agria. The incidence of diseased daughter tubers was higher when the soil was infested than when the foliage was inoculated. C. coccodes contamination of dry stems at harvest (in inoculated plots) was relatively high in all cultivars, with no difference between inoculation methods. Thus, C. coccodes infection not only affects potato yield and the quality of potatoes for seed and consumption, but also contaminates soil and serves as an important source of inoculum for future potato crops.

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