MORPHO - ANATOMICAL CHANGES PRODUCED BY THE PHYTOPHTHORA INFESTANS (MONT.) DE BY. AT THE TOMATO CROP IN GREENHOUSE|
Rodi MITREA, Ion MITREA, Ovidiu TUCA, Catalin STAN,Camelina STEFAN *
Faculty of Horticulture, University of Craiova, str. A.I. Cuza nr. 13, Craiova, jud. Dolj, Romania (E-mail: email@example.com)
*"Tudor Arghezi" Secondary School, Craiova
The plant perceptible reactions at the phytopathogen attack are showed as morpho-anatomical changes, which represent the illness symptoms, as an expression of the accumulated histological, cytological and physiological changes.
In the greenhouses, the same favorable conditions for plant growing and development are unfortunately optimal for the release of many phytopathogens attack too.
For the tomato crop in S.C.R.J. Import Bucuresti S.A. Isalserra Romania greenhouse,
One of the most frequent diseases in the tomato crop, located at S.C.R.J. Import Bucuresti S.A. Isalserra Romania greenhouse, is manna produced by Phytophthora infestans (Mont.) de By.
Material and research method
The Vemone hybrid is the one that was kept under surveillance in the greenhouse tomato crop.
The crop has been set up at the beginning of April through 70 days old hybrid transplants, which were produced in nutritive cubes or flower pots.
In order to achieve the propose objectives, the Phytophthora infestans (Mont.) de By fungus symptomatological tableau has been established by counting the number of characteristical stain and the frequency of the attacked plants.
The counting was done for each organ, determining the most affected leaf and fruit
The tomato plants may be infested by the Phytophthora infestans (Mont.) de By fungus during the vegetation period, from the germination until the end of the period.
The first sign of the disease on mature plants consists in the appearance of some circular, semicircular or irregular stains at the foliole top and, in a lesser degree, on the rest of the leaf, which end up by extending on the whole leaf.
The number of stains has been oscillated from date to date, depending on their localization on the leaf. Therefore on the 28th of May, the stains number on the folioles has been ranged between 69 at the top and 10 at the base of folioles. On the 25th of June the stains counted 74 at the top and 6 at the base of folioles.
Independently of the date when the observations have been made, the higher stains percentage 52.11 % where disposed at the top of the folioles, which allows us to state that the first disease symptoms consist in the appearance of stains at the top of the folioles, while the manna stains are found in a lower number at the base of the foliar limb and on the surface, table 1.
Table 1 The stain number on folioles different position
|The stains localization on folioles|
|Top||Laterally||Base||On the surface|
|Nr.||%||Nr.||%|| Nr. ||%||Nr. ||%|
|28. V. 2002||151||69||45,69||46||30,46||10||6,62||24||15,89|
|25. VI. 2002||142||74||52,11||30||21,12||29||20,4||6||4,22|
As a result of the made observations we have establish that: the stems manna attack manifests at the beginning as little oval or irregular stains, which extend round the stem. The stains are brown or black-brown coloured, the tissues necrosis and become annullable, therefore the stem bend or break easily.
In the event of strong invasion, the tissues go rot, such attack manifest at the branches attachment on the stem. The most characteristically and also the most serious attack manifestation, we have recorded on the fruit, which can be infested in all the development phases.
The most popular and also the most serious attack manifestation, we have recorded on the fruit, which can be infested in all the development phases.
The little fruits turn brown and fall easily. On the green and red fruits of different sizes, the symptoms differ; the stains can be countered at the base, laterally and at the top table 2.
As it can be observed from the table 2 data, the number of stains is related to their localization on the fruit.
The number of stains on the fruits range between 1.52 at the top of the fruit and 4.83 at the lateral part of the fruit. Also, it can be observed that 55.38 % from the total number of stains are placed on the lateral part of the fruit, while the top of the fruit percentage is 17.43 %.
The recorded data justify us to assert that the Phytophthora infestans fruit infection start with laterally parts and rarely on dorso-ventral parts.
The stains on the fruit are soft, brown-olive coloured, turning in the end to brown. Also, it came out that the immature attacked fruits are rugged, hard, while on the mature fruit, the stain are even, yellow-brown coloured and concentrically placed.
On the attacked fruits section, it can be observed that the interior tissues coresponding to the strain, are brown coloured without affecting the placenta.
Table 2. The tomato fruit stain localization at the Vemone hybrid
|The fruit localization||Total|
- One of the most frequent diseases which has been manifested in greenhouse tomato crop is manna, produced by Phytophthora infestans (Mont.) de By. Fungus.
- The number of manna stains on the tomato folioles record different value from a date to another or as a result of their localization on the folioles.
- The most characteristic attack form and also the most serious, in the case of Phytophthora infestans (Mont.) de By. Fungus manifests on the fruit, which can be infested in all the development phases.
- The stains number on tomato fruit as a consequence of the Phytophthora infestans (Mont.) de By. fungus attack, is different function of their fruit localization, the value recorded range between 1.52 at the top of the fruit and 4.83 at the laterally part of the fruit, at the Vemone hybrid.
- Gh. Marinescu, M. Costache, A. Stoenescu, 1986 - Bolile plantelor legumicole, Ed. Ceres, Bucuresti.
- Raicu Cristina, S. Mihailescu, 1982 - Bolile si daunatorii din culturile de legume protejate, Ed. Ceres, Bucuresti.
- I. Voica, 1996 - Bolile frecvente la tomatele din spatii protejate, Horticultura nr.2, pag .7.