Pathogenicity of Swedish isolates of Phytophthora quercina to Quercus robur in two different soils
Publication Type: Journal Article
Source: New Phytologist, Volume 158, Issue 2, p.355 - 364 (2003)
Several studies have demonstrated the involvement of soil-borne Phytophthora species, especially Phytophthora quercina, in European oak decline. However, knowledge about the pathogenicity of P. quercina in natural forest soils is limited.
The short-term effects of two south-Swedish isolates of P. quercina on root vitality of Quercus robur seedlings grown in two different soils, one high pH, nutrient-rich peat–sand mixture and one acid, nitrogen-rich but otherwise nutrient-poor forest soil are described. Pathogenicity of P. quercina was tested using a soil infestation method under a restricted mesic water regime without prolonged flooding of the seedlings.
There was a significant difference in dead fine-root length between control seedlings and seedlings grown in soil infested with P. quercina. Trends were similar for both soil types and isolates, but there was a higher percentage of fine-root die-back and more severe damage on coarse roots in the acid forest soil. No effects on above-ground growth or leaf nutrient concentration between control seedlings and infected seedlings were found.
The results confirm the pathogenicity of south-Swedish isolates of P. quercina in acid forest soils under restricted water availability. Stress-induced susceptibility of the seedlings and/or increased aggressiveness of the pathogen in the forest soil are discussed as key factors to explain the difference in root die-back between soil types.
Uwezekano wa kuambukizwa kwa Phytophthora quercina na Quercus robur katika udongo tofauti: Uchapishaji: Jurnal, Toleo la 158, Toleo la 2, ukurasa wa 355-364: Uchunguzi kadhaa umeonyesha ushiriki wa aina za Phytophthora zinazozalishwa na udongo, haswa Phytophthora quercina, katika kupungua kwa mwaloni wa Ulaya. Hata hivyo, maarifa kuhusu pathogenicity ya P. quercina katika udongo wa misitu ya asili ni mdogo. Mimea ya P. quercina ya kusini mwa Sweden ina athari za muda mfupi kwa nguvu ya mizizi ya mbegu za Quercus robur zilizopandwa katika udongo mbili tofauti, mchanganyiko wa mchanga wa mchanga wenye pH ya juu na mchanganyiko wa mchanga wenye virutubisho na udongo wa msitu wenye asidi, tajiri wa nitrojeni lakini wenye virutubisho. Ugonjwa wa P. quercina ulijaribiwa kwa kutumia njia ya kuambukizwa kwa udongo chini ya utawala wa maji ya mesic iliyopunguzwa bila mafuriko ya muda mrefu ya miche. Kulikuwa na tofauti kubwa katika urefu wa mizizi midogo iliyokufa kati ya miche ya kudhibiti na miche iliyokua katika udongo ulioambukizwa na P. quercina. Mwelekeo huo ulikuwa sawa kwa aina zote mbili za udongo na kutengwa, lakini kulikuwa na asilimia kubwa ya mizizi mizuri kufa nyuma na uharibifu mkubwa zaidi kwenye mizizi nzito katika udongo wa msitu wa asidi. Hakuna athari juu ya ukuaji juu ya ardhi au mkusanyiko wa virutubisho vya majani kati ya miche ya kudhibiti na miche iliyoambukizwa iligunduliwa. Matokeo yanathibitisha pathogenicity ya kusini mwa Sweden isolates ya P. quercina katika udongo asidi msitu chini ya upatikanaji wa maji mdogo. Uwezo wa mimea ya kupanda na kuongezeka kwa uvamizi wa vimelea katika udongo wa misitu ni sababu kuu za kuelezea tofauti ya kufa kwa mizizi kati ya aina za udongo.