stem canker

[gmp]

I love gardening and I am just a beginner!!!!I have 3 rose plants, two in one container and the other in another container. The last one is country rose and unknowingly I bought it with brown streaks and stem canker on the main stem. The growth is poor. Now the problem is spreading to the other container also. one plant is worst hit. and I cut the die back, but it is browning again . the growth is also stunted. don't know what to do. literally crying for help! I don't want to loose it.

[luis_pr]

Cankers are a fungal infection that usually develops during the coldest time of the year. A cut at the end of the growing season allows the fungus to get inside but it has a harder time spreading because the rose is still in growth mode. The cut could have been done by you (think pruning or deadheading) or by canes that cross/touch (the thorns then produce the cut). Once the plant goes dormant, the fungus is able to spread and you see the cankers at the end of winter or the start of your spring season.

Prune the stem about an 1/2" to an inch below the canker affected area. Disinfect the pruners when done.

Minor suggestions: prune to a node and in such a way that canes do not cross (visually recheck a month later); when pruning roses in the Fall, prune at an angle so the callus can form a protective barrier against the canker fungus. You may want to also start spraying for fungal diseases now until the plant has recovered and begun new growth. Those that control black spot will work on canker. Get two black spot fungicides with different active ingredients so the fungus does not become immune if you apply only one (it happens sometimes). Then apply fungicide #1 first per label directions (for example: apply every 5 days); 5 days later, apply the second fungicide per label directions (for example: apply every 7 days); 7 days later, go back to fungicide #1 and so forth.

[gmp]

Thanks a lot for your help. . My problem is the whole stem except a small gap is brown. The is no 1/2 " inch space for me to cut.
I disinfect the pruners with rubbing alcohol. Now my plant is sooooo small. I made another blunder also. I stripped off all the leaves because of mites. The plant was standing still (except browning) for a whole week, but lucky me today I saw few shoots to start. It has not come out completely, but I am still happy to know there is still some life in my plant. . What will happen to my plant if I could not cut the stem, but if the plant is still growing? my question may be silly, but I love my plant. I usually use parker neem oil spray for my plant. Is it ok?

[luis_pr]

Fungal growth is reduced during the growing season while the plant is in growth mode so it may continue growing but is does not bode well if the new growth turns black/purple-ish. During this time, you could try to propagate the plant via cuttings and see if they take. When growth slows in winter (or a hot summer), the canker could start all over again.

How big is the unaffected part? Can you cut a smaller sliver below the infected area, instead of 1/2"? The more you cut, the better the chances are you the piece left will remain ok but if you have little space, well, try it (but do that a-f-t-e-r you decide to to propagate and a-ft-e-r you have gotten several cuttings).

[gmp]

This is the first plant. Brown streaks are at the base. Would like to know if this plant is also at risk, since both are in the same container. Some of the cut stems have turned black. But it is not coming down.

[gmp]

This is the second plant. Upto me this is the worst hit as I keep on cutting the stem, the canker spreads and now the complete stem except at bit at the base is brown. could see it at the middle of the plant.

[gmp]

This is the country rose which I have brought with stem canker. I bought it with the streak of brown on the main stem itself. Have I made anything wrong. I think this is the one which has spread the fungus. Is my conclusion right. Please help me.
Please tell me how to prune this. Now the new leaves are very pale green and the older one are getting brown. Anything I can do to save this plant

[luis_pr]

1st plant picture: I would not worry about the brown streaks at the base although I can picture some friends of mine adding Elmer's Washable Clear School Glue to protect the bark some more. I would, for sure, remove the endings that are turning black by pruning below them, say 1/4 to 1/2 an inch below. Cut where the bark is green, not where it looks yellow or black/purple.

2nd picture: I would remove the stem endings of the middle stem, below the affected area. I would also cut the stem ending of the leftmost stem, below the affected area.

3rd: I would not worry about the brown streaks at the base of this one either. There are spots of what could be canker or black spot that developed on the stem. I would cut the two leftmost stems in the circled areas in the edited picture below. The middle stems is a "I am not sure". It may also have to be pruned (see where I wrote "cut???" and drew a line in the picture). Look carefully for my changes; they came out kind of small. Hoipe you can see them.

It is hard to tell if those canker or just a black spot infestation in the injured areas. So just monitor it and take action if the affeted area gets larger. See if it develops more into a true canker or if the black spot fungicides clear that away.

https://i150.photobucket.com/albums/s111 ... 74fa68.jpg

In addition to using the fungicides, here are a few good housekeeping techniques: Water early in the mornings. Make sure the pot has unclogged holes where the water can exit through. Do not let the pot sit in water for long periods of time. Water the soil, not the leaves (so do not do overhead waterings). Allow the soil to get almost dry before watering; insert a finger into the soil to a depth of 2-3 inches (5 to 7 cm) and see how it feels... wet?, moist? dry?. Checking the soil moisture in this way will make it difficult for the fungi to thrive.

Too much watering can deprive the roots of oxygen, cause root rot, can leech out a lot of nutrients/minerals and can cause the leaves to temporarily turn a different shade of green. If the light greening of the leaves is temporary (reverts back to normal color on its own in a few days) then do nothing. Otherwise, if the leaf veins stay darker than the rest of the leaf, add acidifying compounds (iron sulfate, iron-chelated liquid compounds, garden Sulphur, greensand, etc). Browning and yellowing of leaves can be a plethora of things so see how the shrub does if you only water the soil when the soil feels almost dry to the touch.

[gmp]

Amazing explanation! thanks a lot for the great information. This is going to be the first thing tomorrow morning. Now I feel a little bit relaxed, as I know what to do. I shall also take care about watering and fungicide. Let's see. I'll update u.

Thanks a lot

One more clarification what are those brown streaks?

Thanks in advance.

[luis_pr]

There is no way to find out what caused that but it is damage that occurred at some point. It resembles damage from thorns, like when a cane rubs against another cane. But it is quite unusual to see the damage there (down at the base). A problem during Shipping & Handling?, etc.

[gmp]

Thanks luis, today I pruned and waiting with my fingers crossed. will update u.

[gmp]

The first one and the third one has completely gone. The second one is flowering. Thank you luis-pr.

[luis_pr]

There should be another growth spurt & more flowers when the temps go down and stay down.

[gmp]

thanks a lot. your words are very much encouraging, for a beginner like me.

[gmp]

You are right. Now the plant is thriving. I will post few photos later. Thanks a lot for the suggestions.

[luis_pr]

Good to hear that your plant is making progress.

Roses around here are still "semi-dormant" due to the high summer temperatures. As is normal during this time of the year, the number of blooms is greatly reduced with most rose shrubs looking almost all green.

A few of them have blooms but they are quite small compared to normal and-or the colors look as if they were wrong. For example, bicolored ones like Scentimental bloom small and almost all pink (meaning pink/red with few or no white stripes).

Once we get to September, temps will come down, the blooms will revert to normal and we will get a big flush of blooms. For now, I am not even fertilizing these heat stressed plants, just watering.

[gmp]

If the blackspot is below the bud union, will it be possible to save the plant? as we could not cut the affected portion from the plant. First, will it affect the plant? If so, what should I do? This is just to know. Thanks in advance.

[luis_pr]

If the canker has spread there, it may not be possible to help. You can continue the fungicide treatment to see if it helps and be ready to get some cuttings.

[gmp]

This plant seems to have some deficiency. Googled, but could not find out what the problem is. Could not differentiate between the deficiencies. Please tell me what I should do now. There are many buds but nothing seems to take off.

[gmp]

Thank you luis-pr. This is how the second rose looks like now.