ROSES

_mangifera_

Powdery Mildew


Powdery mildew is another widespread and serious disease problem of roses. It is caused by the fungus, Sphaerotheca pannosa var. rosae and produces a grayish-white powdery substance on the surfaces of young leaves, shoots and buds. Infected leaves may be distorted, and some leaf drop may occur. Flower buds may fail to open, and those that do may produce poor-quality flowers. It can occur almost anytime during the growing season when temperatures are mild (70 to 80 癋), and the relative humidity is high at night and low during the day. It is most severe in shady areas and during cooler periods.



Natural Controls

"Forces of Nature"
Limiting factors are temperature and humidity levels.

Potential Indirect Treatment Strategies

Cultural Management
Avoid heavy applications of high nitrogen fertilizer and heavy pruning during the growing season. This causes excessive succulent and weak new growth which is ideal habitat for powdery mildew.

Habitat Modification
Replace particularly susceptible and problematic plantings with disease-resistant species/varieties or alternate plant species.

Design and Construction
Avoid using species/varieties that are known to be particularly susceptible to diseases as a major design component. Choose varieties of susceptible species known to be resistant to powdery mildew.

Potential Direct Treatment Strategies

Manual
Powdery mildew cannot survive if there is a film of water on the leaves or stems. Washing new growth with a heavy stream of water removes spores and also helps prevent remaining spores from germinating. Begin as soon as conditions are conducive to growth of the disease at intervals of once or twice a week for a few minutes; early afternoon is the best time. Continue until new growth matures and resume when other flushes of new growth coincide with favorable environmental conditions for the disease. Although wetting the plants can enhance the likelihood of black spot and rust, optimum conditions for both diseases typically do not occur simultaneously.
Prune and burn infected leaves, petals, and canes during the growing season as soon as detected. If plants have been heavily infected the previous growing season, prune to within 10-15 cm of the graft. In mild winters and generally mild climates such as in the coastal regions of the Pacific Northwest roses may not go fully dormant, making disease removal more difficult. In this case roses should be "pruned into dormancy" and rose litter removed in January. Any small, weak wood that would not support a bloom should be removed. Experience at the Owen Rose Garden in Eugene, Oregon indicates that healthy canes are rarely bothered by disease unless located near infested, weak stems.


Physical
Mulch rose bushes and other susceptible shrubs after fall cleanup and again after mid-winter pruning. This helps to contain spores under the mulch to minimize spread.

Biological
Research relating to the use of several fungus species as biocontrols for powdery mildew is being conducted at the University of Oregon and in Israel.

Chemical
Safer Natural Garden Fungicide is a new fatty acid-based soap product that is reported to be effective at preventing and eradicating powdery mildew. Apply every 7-14 days during cool, dry weather when roses are in an active growth phase. This new product is not phytotoxic to roses and most other ornamental plants and also kills pest mites but not beneficial mites.
Antitranspirants (e.g., Wilt Pruf) form a barrier between disease spores and leaves. Various research and field tests, including at Longwood Gardens in Delaware, have indicated antitranspirants to be at least as effective as conventional fungicides in controlling powdery mildew. However, further research is needed to confirm this, refine application timing and techniques, and verify that the antitranspirants don't cause any undesirable effects when used in this matter in various climates.

Baking soda may also be effective at controlling powdery mildew; research is being conducted in Japan and by the Henry Doubleday Research Society in Great Britain. Sulfur is effective at controlling powdery mildew and can be used in conjunction with the other non-chemical methods described.

If conventional fungicides are necessary, limit their application to individual plants. They have a tendency to cause secondary outbreaks of pest mites. (See Black Spot prescription for quote from Olkowski, Daar, and Olkowski about fungicides.)

***sumber internet***

Ini mungkin boleh tolong nazurah..

_mangifera_

ok sekian dulu nak blk kg

cikna99

Utk ros, biasanya mmg kena bg baja utk long life maaa.. Cikna prasan gak, sometimes bila daun2 dah byk mula menguning, pastu ada dot2 hitam, cikna penah trim bg cantas pendek n buang daun yg bermaslah. Gembur blk n bg baja,siram jgn sampai berendam.. Lps 2 ke 3 wks, shd be ok..Daun mula sihat semula n buds baru akan keluar.

Mungkin kena guna baja berbeza utk dptkan perbezaannya..
Klau nak tlg blikan baja tahi kelawar tu n pos, bole jgk.. mcm forumer lain... saje2 menolong..

_mangifera_

Originally posted by cikna99 at 6-2-2008 04:27 PM
Utk ros, biasanya mmg kena bg baja utk long life maaa.. Cikna prasan gak, sometimes bila daun2 dah byk mula menguning, pastu ada dot2 hitam, cikna penah trim bg cantas pendek n buang daun yg berm ...

Boleh juga tp kena tunggu baja sekarang nih abis..kang ngamuklak cik abg

alifinara

Mawar putih untuk mama....

razifah

Tajuk lagu kan? MAWAR PUTIH UNTUK MAMA

ms_aja

salam & hai......

lagu tu sape nyanyi?

_mangifera_

Semalam duk pruning pokok ros..sekali masa selak bawah daun..tgk mula ada warna putih..halus jer..alahai baru jer nak sihat..pe lai buat mandian daun..saya kesat bwh daut tu ngan span basah..tak tauler berkesan ke dak..

mekma

ok tak harga pokok rose RM 16.00, ari tu mek tgk kat jusco melaka...

_mangifera_

uik besor mana pokoknya?..cam mahal jer..kat tmpt saya dlm RM5-RM13 jer..

mizahanan

tempatku 1 polibeg rm5.. beberapa bunga+bud

ms_aja

Originally posted by _mangifera_ at 13-2-2008 11:51 AM
Semalam duk pruning pokok ros..sekali masa selak bawah daun..tgk mula ada warna putih..halus jer..alahai baru jer nak sihat..pe lai buat mandian daun..saya kesat bwh daut tu ngan span basah..tak  ...

ok gak tu..kalo saya spray jek...pokok besar..tak leh nak lap satu2 dh..

mizahanan

kalo spray dgn cecair bwgputih ok dak?

mekma

iya ke..besar lah jugak..kalu kira bunga tu ader ler 6-8 kuntum, yg kuncup pun ader

_mangifera_

Ms Aja;
Sebelum balik kg CNY tu saya dah gondolkan pokok ros tu..kalau dak jenuh gakler..Semalam tgk pucuk baru nampak ok.

Mizahanan;
Cecair bwg putih tu dpt dr mana yer?

_mangifera_

Mekma,

kalau tak tmpt saya pokok RM5-6 tu dalam polibeg, bunga nya adaler 2-3...tu kalau bunga besarlah..tp kalau bunga kecik mmg meriahler..

Yg RM8-13 lak yg ni dah siap dalam pasu..dlm pasu tu dia letak 3 pokok berlainan warna..tp tu dia lah nak tukar pasu tu yg leceh nanti.

ms_aja

Originally posted by mizahanan at 13-2-2008 03:24 PM
kalo spray dgn cecair bwgputih ok dak?

blum penah buat lg lak..buat ke...beli? yg penah baca yg bena ni susah nak mati..pastu suka dgn panas lg panas lg cpt dia biak..cara mudah spray bwh daun dgn air ye....bena dewasa ni takut air..tp yg leceh pulak..telur dia tak lut air..sbb dh terlekat kt bwh daun tu..

_mangifera_

Originally posted by ms_aja at 14-2-2008 10:59 AM



blum penah buat lg lak..buat ke...beli? yg penah baca yg bena ni susah nak mati..pastu suka dgn panas lg panas lg cpt dia biak..cara mudah spray bwh daun dgn air ye....bena dewasa ni takut牋...

Ms aja, haah dia tak suka air..sebenarnya office mate saya

mekma

ooo ok gak tu...ada sesapa kat sini tau area melaka nursery mana yg jual pokok rose yg cun2 n murah...ader satu nursery mek gi, pokok rose tu mcm nak mati je

mizahanan

fera, aja..

cecair bwgputih tu buley buat sendiri.. tumbuk bwg putih pastu campur air letak dlm spray pump tu.. spray kt perosak yg warna putih tu.. perosak tu x suka cecair garlic tu.. petua dr jiran.. sbb die tgk saya suka beno dgn bunga sejak kebelakangan ni.. saya x sempat cube lagi..

tp kt mane saya bace.. thread ni gak kot.. guna air sabun dah ok...