ASK THE CONSULTING ROSARIAN
by John Moe, Master Rosarian
Q - During the “early bird” session at the last meeting you talked about suckers as being new growth from below the bud union. But I think that I might have an own root rose, but if it has no bud union, can there be a sucker? If I see what might be one, what should I do?
A – You are correct that an own root rose has no bud union, so if you are not sure it is an own root rose, and you see what you think might be a sucker, just let it grow for a bit. An own root rose can have a sucker, but it is very rare and can come from a root anomaly. Suckers normally emerge and rapidly shoot above the rest of the rose bush in a matter of weeks. And because it is produced from below the bud union, it “sucks” the nutrients up before they can get to the rose variety you purchased. Hence the term - “sucker”. Eventually they will kill the rose variety you purchased, and you are left with nothing but understock. Suckers are quite easily distinguished from the real rose, in that they have 7 leaflets making up the leaf, are very thorny, are normally smaller with a lighter green as opposed to a tad darker green with usually 3 and 5 leaflets in the leaf of the rose. If it is appears to be a sucker, it is best dealt with by digging down, pulling and twisting it off - rather than cutting it with your pruner. But if the new growth and leaves look like the rest of the bush, it probably is a new basal cane on your own root rose.
Q – When it comes to working in the rose garden, I am of the more ‘laid back’ type trying to do the least amount of work, as I would rather be on the golf course. So, when it comes to lime and fertilizer, can I do both at the same time?
A – Before I answer your question directly, let’s take a moment and review why we do those tasks. Simply stated, we are fertilizing to provide food for our roses. But as for lime, that is a tad different. Lime is usually added to acid soils to increase soil pH, but if we don’t know what the pH of our soil is, how do we know if we should add lime, and if so, how much? This is why it is always good to have a soil test!
Our normal pH in this area is about 5.2, which is quite acidic, but if you have been liming on a regular basis, your soil might be closer to the desired range of 6.0 to 6.5, which is just slightly acidic. If the pH drops back down to the mid 5’s, your roses can't adequately absorb nutrients, including those provided by fertilizer -- such as nitrogen, phosphorus and potassium. Lime raises your soil's pH so the roses can get the food they need.
Now to answer your question - you can apply both on the same day but, if you need both, I believe it's best to stagger the applications. If you know, or a soil test shows that the pH is too low, go ahead and lime a week or so before fertilizing. If your pH levels regularly stay between 6.0 and 6.5, you don't need to apply lime every spring and fall. My last complete soil test indicated the pH to be 6.4, with a recommendation for no lime, so this year I am going to defer until fall.
Q – I am out in the garden crawling around scratching in some fertilizer, and see on a few bushes what looks like a frothy white mass. What am I seeing, and what should I do? Will it damage my rose?
A – What you are seeing is the froth or spittle that the immature spittlebugs (nymphs) use to hide on plant tissue when they feed. And yes, there is a bug inside that froth! Spittlebugs pierce the plant stems and suck plant juices, and can stunt some plants, but the damages are minimal, and the bugs can be picked or washed off with a forceful stream of water. The spittle serves multiple purposes in that it protects from predators, insulates them from extreme temperature, and prevents them from dehydrating. The spittlebug froth protects the insects from chemicals as well. Fortunately, insecticide chemicals are rarely needed.
Q – I have been moving the mulch away from the stems, but there was some new red growth poking up through the mulch on some, so I left them until I could check. Are these those dreaded ‘suckers’ that I have heard you mention? Should I just rip them off? If not, what should I do?
A – What you are most likely seeing are new basals; however, there could be some suckers. This is a good sign that your bush is alive, and ready to get growing for the season. New growth is very tender, and you can easily damage it if you are not careful.
One of the first things to do is to carefully remove the mulch so you can get a good look at them. If you get carried away with a shovel or start digging away with your hands you can easily break them off.
One of the best ways to avoid damage is to use a hose and gently wash away the mulch, so as not to disturb the new growth. Now check to see if any of it is coming from below the bud union. If it is not, it is a new cane. If it is, it is a
sucker and should be taken off. More about suckers next month – stay tuned!
Q – The Puyallup fertilizer I ordered can be picked at the meeting in April, but I heard that I should wait a bit before using it – why is that? If I must wait, when should I start? And what about newly planted roses?
A – In past years we have usually recommended that you wait a bit, as the soil needs to warm to about 50 degrees for the microbial life in the soil to break down and release the nutrients into the soil in a form that the plant can absorb and use. However; this year has been somewhat warmer, so that when you do get your fertilizer it should have warmed enough so that you can have the first application of fertilizer by the end of the month.
We are in one of the cooler microclimate areas, so I will most likely wait a week or so. Fertilizing with chemical fertilizer when the soil is cold is just wasting it! Natural (organic) fertilizers e.g., Alaska Fish emulsion or alfalfa can be applied earlier in the season, since they remain in the soil for longer periods. They have an easier time of breaking down than the chemical or inorganic types.
Now for those newly planted roses – what we want them to do is to get their roots established. A lot of the early growth comes from food and moisture stored in the canes, not from newly forming feeder roots. In other words, they really don’t need food at this stage, so it is best that you wait till the first bloom cycle! All synthetic or chemical fertilizers are salts, and all salts interfere with the ability of plants to obtain water. Salts draw moisture out of those tender new feeder roots, resulting in fertilizer burn, which can severely damage them.
When we do fertilize, it should never be applied to dry soils, as it is apt to burn the surface feeder roots almost instantly. So be sure to water deeply before and thoroughly after applying.
Q – I made a few hardwood cuttings last fall as we discussed, but I am unsure as what to do now. How long to leave them before I can move them?
A – When you start to see new growth in the spring, don’t be too hasty to mess with them. On a warm day remove the cover for an afternoon, replacing it for the night. This will allow the cutting to have a better oxygen transfer and start to harden off. When the nights are not quite as cold, like after mid May, it can be left off.
Keep your cuttings well watered in spring and summer, and fertilize normally during the growing months. You can encourage additional shoot formation and branching by removing flower buds. It is best, if you can, to let them to grow in their temporary home until fall, when they can be safely dug up with as much root as possible and transplanted to a permanent location.
Q - I see that, even with all the dry days we had, there is still some mildew on my bushes. I haven't been the best at keeping up the spray program the last month or so. But should I really put a lot of effort into it now - since pruning isn't too far away ?
A - Powdery mildew can be severe in warm, dry climates. This is because the fungus does not need the presence of water on the leaf surface for infection to occur. However, the relative humidity of the air does need to be high for spore germination. Young, succulent growth usually is more susceptible than older plant tissues. I would hope that most of you would have kept up your spray program last month in anticipation of the Fair. With that said, I haven't been a lot better either of these last few weeks as I have been gone !! We can still have some nice blooms even though now it's Fall. Do not use any more fertilizer, & keep up with your spray program. What I did before my last spray after I returned was to prune some badly diseased cane tips down some, although they will grow some after my pruning. There is not much time left for bloom production, so why waste spray on those diseased cane tips ??
Q - I enjoyed your 'early bird' session at the last meeting on some things to do before we get into winterizing our roses, but I was disturbed to hear about the Japanese Beetles. The photo of the damage they can do to a rose bloom was just awful !! Although they are not up here yet, they most likely will be. Can you tell us more about them & what we can do ??
A - Yes they have been observed in Portland and are a big threat in that they don't discriminate on what types of plants to feed on, attacking more than 300 different kinds !! They lay eggs in the soil during June, which develop into tiny white grubs that overwinter & grow in the soil. They emerge from the soil the following season as adult beetles and begin feeding in groups in June, which is why damage is so severe.
The lifecycle of the adult Japanese beetle is barely 40 days, but they do lot of damage in that time. Those of us going to the District Conference have been promised an update, so we will know more then & will pass on more information to you over the winter.