摘要:

The results of field surveys carried out in citrus groves of Apulia and Basilicata in Italy to clarify the etiology of a decline condition associated with root and foot damage of citrus are reported. Field observations and laboratory tests have shown that the most frequent causes of citrus decline are root and foot infections byPhytophthoraspp. The species isolated wereP. nicotiunaevarparasiticuandP. citrophthora;the former was the species most often isolated from both the soil and the feeder roots. Less frequently,ArmiNuriasp., frost damage and rodents were identified as additional causes ofdecline. Finally the role ofcultural factors in the decline caused byPhytophthoraspp. is discussed.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01183.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Avocado root rot caused byPhytophthora cinnamoniis a major limitation for avocado expansion in the Canary Islands, as it is in other producing areas of the world. To date, no germplasm with resistance potential has been found among West Indian avocados, which would convert this type into an ideal rootstock for use in infested areas such as the Canary Islands. Our aim was a thorough screening of the local West Indian population, descendants of seedlings brought to the Canaries from the Caribbean in the early 1800s. Our selection methods were based on those used by Zentmyer in California (US) since 1960 (nutritivesolution tank, with controlled aeration, pH, and temperature, to which inoculum is added), which gave rise at that time to several resistant/tolerant Guatemalan and Mexican rootstocks. We also screened using pots filled with naturally infested soil. The plant material tested was: (a) West Indian seeds from the original, local population; (b) seeds of the Guatemalan x West Indian hybrid Gema, taken from 20‐year‐old local trees growing in highly infected groves; (c) seeds of the salt‐resistant Israeli West Indian cv. Maoz. Also tested for comparison purposes were seeds of Mexican and Guatemalan avocados. Inoculations were done using theP. cinnamomiA2 strain, taken from proved diseased trees found in the Canaries. At present, one West Indian plant has survived the selection in a first trial, while 38 have survived in a second trial. One Mexican plant (cv. Topa‐Topa) has survived in a third trial. Resistant material is now being reproduced both by tissue culture and by the etiolation te

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01184.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In the last 20 years, seven differentPhytophthoraspecies(P. cambivora, P. hibernalis, P. citrophthora, P. capsici, P. cactorum, P. drechsleriandP. infestans)have been determined in Turkey on chestnut, citrus, pepper, strawberry, melon, and potato respectively. Two of them,P. citrophthoraandP. capsici, which attack citrus and pepper, are very destructive and have the greatest economic importance.P. citrophthorahas caused approximately 15% fruit losses every year and 8–30% infection on a susceptible lemon cultivar in Cukurova region.P. capsiciis very dangerous for pepper‐spice and pepper‐paste production because it causes up to 100% drying and killing of pepper plants under conditions of poor drainage and incorrect irrigation practices.P. cambiuora, which causes the ink disease of chestnut, has spread from the Black Sea coast to the Mediterranean; about 20 000 chestnut trees have been killed by this organism from 1952 to 1970. Recently,P. infestanson potato is achieving importance, as the potato area increases. The other species ofPhytophthorado not have any economic importance and only first records have been

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01185.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Phytophthora frugariaecauses red core root rot of strawberries. Although the disease is probably most acute in northern Europe, serious outbreaks have been reported from a number of Mediterranean countries, especially France and Italy. Leather rot of fruit and crown rot, which are caused byP. cuctorum, can also be severe problems in warmer climates. Both fungi survive in soil for long periods, but the most common form of spread is in diseased planting material. Sensitive tests have been developed to detect red core in planting material, and been used to effect in certification schemes. Root rot of raspberry has gained prominence in the last 10 years in Europe as raspberry growing has expanded, but the disease has been known for many years in France. Nine species ofPhyfophthorahave been recovered from affected plants, but two of these, one with affinities withP. megasperma, andP. cumbiuora, are responsible for most major outbreaks. The other species are only troublesome where drainage is poor. Again, spread is mainly in infected material. Few raspberries are resistant to root rot, but some wildRubuPspp., blackberries and raspberry x blackberry hybrids are resistant and may be useful in breeding programmes.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01186.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In order to establish a genetic model of the resistance toPhytophthora cupsiciinCapsicum annuumgenotype‘Line 29′, three experiments were conducted which included, as well as‘Line 29′, the susceptible genotype‘Morron INIA 224’and several of its F1, F2, F3and backcrosses. Plants with 4–6 leaves were inoculated by irrigating the culture substrate with a zoospore suspension of isolate B 1. The F2test was applied to the segregating generations to test whether there were one, two, three or four genes involved in the resistance. Additivity and equal weight of all the genes in the final effect were assumed. The hypothesis that best explained the results obtained was the one that assumed three genes in‘Line 29′; at least four alleles had to be present in any genotype for it to behave as resistant. The possible influence of isolate aggressiveness and inoculation method on the res

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01187.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Trois phytophthoroses des cultures dans la région méditerranéenne du Monténégro sont présentées: la gommose des agrumes, maladie connue depuis longtemps, mais dont l'importance est devenue négligeable grâce à la pratique du greffage;Phytophthora capsicisur poivron, constaté pour la première fois dans le Monténégro il y a une dizaine d'années, etPhytophthora nicotianaevar.nicotianae, provoquant le pied noir du tabac, connu en Yougloslavie seulement depuis 1983. Les phytophthoroses du poivron et du tabac restent toujours des maladies potentiellement importantes dues à la nécessité d'irrigation de ces cultures et á la difficulté d'une lutte c

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01188.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Aerial damage on transplanted seedlings ofEucalyptusspp. was recorded in Italy for the first time. In 1987 a widespread infection was detected in the eucalyptus nursery of the Ovile Farm, Rome. It occurred only onE. globulusand was subject to sprinkler irrigation. In 1988 the disease occurred exclusively onE. delegarensisandE. regnans.The agent, which attacks leaves, petioles and shoots, was identified from the morphological and physiological characteristics of the isolates obtained in each year asPhytophthora nicotianaevar.nicotianae.

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01189.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The effectiveness of fosetyl‐A1 against citrus foot rot caused by Phytophthora citrophthora has been evaluated in a 25‐year‐old orchard of sweet orange cv. Tarocco, showing severe symptoms of the disease and in a 10‐year‐old orchard of the clementine‐type mandarin cv. Monreal, apparently healthy. All the trees were grafted on sour orange. In both orchards, three sprays at 200 g a.i. per 100 1 were applied in May, July and September for 3 years. The results were evaluated on the basis of yield and fruit quality. Trees of cv. Tarocco had yield increased by 25–44% whereas cv. Monreal yielded 3–16% higher than the unsprayed trees. Fruits of orange cv. Tarocco were collected from trees sprayed with fosetyl‐A1 and plunged in a water suspension ofP. citrophthora.Fruits treated 11 days before inoculation showed an infection rate of 8.7%) whereas those unsprayed were 77% infected. Fruits inoculated 21 days after the treatment with fosetyl‐A1 were 32% infected whereas those unsprayed were 91%, infected. In other trials, trees of volkamer lemon were sprayed with a conidial and mycelial suspension ofP. citrophthoraat different times after application of fosetyl‐A1. The number of infected fruits and leaves in the unsprayed trees was very high (up to total leaf drop) and decreased sharply with the numb

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01190.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Phytophthora gummosis and phytophthora root rot are the most important fungal diseases of citrus in the State of São Paulo, Brazil.Phytophthora citrophthoraandP. nicotianaevar.parasiticaare the main species that incite both diseases in all the citrus‐growing areas of the State. Studies on the control of gummosis and root rot with systemic fungicides have been under way in the State since 1980. The efficacy of fosetyl‐A1 and metataxyl to control gummosis incited by both fungi in lemon and sweet orange trees was confirmed. The best control was achieved when foliar sprays of fosetyl‐A1 were combined with soil applications of metataxyl. The best timing was determined for application of these systemic products to control gummosis in the

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01191.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

According to the results of bioassay studies, 50 p.p.m. and higher dosages of fentin acetate inhibited the growth ofPhytophthora citrophthora in situ.Zoospore movement ofP. citrophthoravaried between 3 and 15 min at 0.5, 1, 10, 100 and 500 p.p.m. fentin acetate. The fungicide also inhibited fruit infections caused byP. citrophthorazoospores at 5 p.p.m. concentration, and protected citrus seedling roots against infection by the fungus at 20–50 p.p.m. concentrations in water culture. Fruit infection was significantly lower in fentin acetate plots than in those without fungicide applications. Stem infection was 15.5 and 8.3% when fentin acetate was applied one or three times respectively as a soil drench in a lemon orchard, but reached 74.9%) in control plots. Fentin acetate treatment decreased inoculum potential to 1/2 and 1/128 in the root zone from the first to the third applicatio

ISSN:0250-8052    

DOI:10.1111/j.1365-2338.1990.tb01192.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY