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Agastaches and Salvias: Salvia with mealy bugs

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Forum: Agastaches and SalviasReplies: 12, Views: 219
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3gardeners
Mableton, GA
(Zone 7a)

December 19, 2007
11:24 PM

Post #4311493

I'm new to Salvia and to top it off this is the first time I have EVER had mealy bugs. I noticed them on my black and blue, 3.5 foot tall salvia, but did nothing at first because I was busy, forgot about it, didn't think much about it... Anyway, I went back to that part of my garden a couple weeks later and the salvia was dead looking on the branches (half of them at least) with the bugs AND they were spreading to sages and lavenders and across the ground from one plant to another.
I did lots of reaseach and came to the conclusion they were mealy bugs (although, I didn't see any of them crawling). I sprayed with insectisidal soap, nothing, ~ week later I used some pesticide I had in the garage that said it killed meally bugs. They stopped spreading , but there was no difference in the way they looked. Just white up and down stalks. I cut the dead parts of the plants off.
Now we are finally getting winter weather, and the remaining dead salvia stalks are still there with this white stuff all over them.
Question: Since the season is over, I was planning on cutting back the salvias and sages and other dormant plants now.
What can I do to encourage these plants to rebuild their strength and return next year?
Or are they most probably already dead?
Should I dig them out and sacrafice possibly live plants to erradicate the bugs?

The white stuff seems to just sits there and stare me, and I just stare back because I don't know what to do.

Any help would be appreciated. Thanks!

(this photo was taken this summer)

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3gardeners
Mableton, GA
(Zone 7a)

December 19, 2007
11:25 PM

Post #4311495

here's one more photo

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Rich_dufresne
Candor, NC

December 19, 2007
11:40 PM

Post #4311540

Ants are the primary vectors for mealy bugs, since they produce honeydew that the ants crave. They can make a mess of my stock plants if I do not control them.

They can be easily killed at the nymph stage, which is when they look like off-yellow near microscopic dots. The adult males look like small mosquitoes and fly (a telltale sign), and the fertilized females are the stationary ones that lay their eggs underneath themselves and then die, allowing the first instars to build up strength. If you wipe off the white fuzzy mass, you will find the babies underneath as a soft yellowish powder.

Since they need to be exposed for insecticide and predators to kill them, I spray the infected sites with a fine jet of water to dislodge them, the same way you remove sucking aphids from stems. In the case of the aphids, the jet tears off the aphid from the stem, leaving their stylets stuck in the stem and making the aphids unable to reestablish themselves on a fresh stem.

After the mealys are exposed, spray the plant with your insecticide (Safer soap or a harder chemical). Control the ants at the same time with a bait.
3gardeners
Mableton, GA
(Zone 7a)

December 25, 2007
3:46 AM

Post #4325458

Thanks for the help. Can you give me a bit more?

So, I guess you are confirming for me that they are indeed mealy bugs?

Also, you do believe that the plants will return...they have not suffered irreperable (sp) damage?

Are these remnants of the white bugs still alive? dormant? Or are they a totally new crop if they return next year?

Do I need to treat the soil in any way?

Thanks again. I want to get the jump on them next year!
Rich_dufresne
Candor, NC

December 25, 2007
4:30 AM

Post #4325519

Oh yeah, they are. I have my own stressed stock plants.

The plants are weakened, but still vital.

Mealys are omnipresent, and will attack plants under stress. Check root zones for friable and fertile soil, correct amount of water. Humus in the soil helps.

Vigilance and timely pruning, fertilization, and spraying are the best controls along with soil condition.
bermudakiller
Union Grove, AL

January 15, 2008
2:05 PM

Post #4404839

if safer's doesn't work well for you, if doesn't for me, try parrafenic oil, usualy sold as sunlight oil. it is a petroleum based oil, but it isn't a poison, it suffocates the blasted things and the bugs don't get resistant to it, like harsher chemicals. Salvias are not listed as safe, so try 1 and see what happens, damage usually shows in a day or 2, read instructions and here in the humid South, I stay at least 5 degrees under max safe temps. Never got them on my salvias but it sure wipes them off the camellias and hollies. it is not a systemic spray, so you need to reapply every week to 10 days till they are dead, not gone, they tend to adhere long after they are dead, they dry and stick, scales, similar pests do the same, peel one off and see if it is soft underneath, if soft, alive or recent dead. hard and dry, dead. Good luck, persistent and damaging but not immedieatly deadly
Rich_dufresne
Candor, NC

January 15, 2008
3:01 PM

Post #4405029

One other thing about mealy bugs. They can also attack roots. Lift a plant out of its pot and check for white fluffy, fibrous looking blotchs, usually an eight of an inch or less. The mealys might look more like a white fungus attack at first. This is probably how they overwinter as well, and ants are probably the way they get there. You can help a plant recover by hitting the root ball with a drench. I am not sure safer soap will work here, especially if the plant is frequently watered. Since the natural media for the roots is moist, the root tips might be damaged by the treatment. Here I tend to use the harsher chemicals, especially if it is a rare plant and there are few or no other clean stock plants.

It is a good idea to burn the cut back contaminated plant material, since it harbors pest eggs and pupae as well as tissue infected with both dormant and active pathogens. The material should be dry when burned. When you do this, make sure you are not violating outdoor burning bans. For the homeowner, the burn will likely be over in a few minutes. With my collection, I need to watch the burn for as much as 40 minutes..
StonoRiver
Johns Island, SC

January 23, 2008
1:39 AM

Post #4440633

I never had a problem with mealy bugs in my whole life, until 2 years ago. Now I'm suffering payback! Safer Soap is always my first line of defense. They laughed at it; in fact they seemed to thrive on it! So I started up the scale, first with pyrethrin, then rotenone, you know the drill. I could knock them down, but never get rid of them. They'd be back within 2 weeks. That white cottony stuff they put out protects the bug underneath pretty well. Unless you use a jet spray like Rich_d suggested, the insecticide won't get through to the bug. I've finally got them under control (but not eradicated!) by using a combination of bermudakiller and Rich_d's approach. I mix up a batch of sun oil, pump my sprayer up to the point where I think it's going to explode or I'm going to suffer a heart attack (whichever comes first), and blast everything in sight. Unfortunately, "blasting" them also spreads them if the oil doesn't actually get to the insect to kill it. I'll be doing it again this year I'm sure, but I'm "going to ground" this year with DY-Syston or Merit in addition to the oil blast. But oil gave me the longest respite from these nasty things.
3gardeners
Mableton, GA
(Zone 7a)

January 23, 2008
2:44 AM

Post #4441053

Is sun oil vegetable oil?

I was also thinking about using that Bayer Advanced systemic bug killer.

I've never had these darn mealy bugs.
WHERE did they come from! Why me, WHY ME! ;-)
Rich_dufresne
Candor, NC

January 23, 2008
4:40 AM

Post #4441576

Did you have a very hot August and drought, like we did in central North Carolina? They may have always been there, and discovered some stressed plants. Ants will certainly reinforce their sweet tooth for particular plants.

Systemics would get rid of both the foliar and root mealys. The effectiveness would be increased if the plants are made more vigorous by adding compost (worm castings work well). Tomato plants with phosphorus deficiencies attract whitefly, so there may also be a nutrition imbalance, like too much nitrogen and not enough potassium, phosphorus, or trace elements like boron or manganese. An incorrect pH might lead to the inability to absorb micronutrients like iron. Finally, some plants can get too much of particular nutrients. South African proteas like phosphorus poor soils and our normal fertile soils will kill them.

As new plants are introduced from the wild, collectors should record the soil type and exposure to help settle problems like these.
3gardeners
Mableton, GA
(Zone 7a)

January 23, 2008
4:47 AM

Post #4441594

Here's my plan.

In the spring I will:
1. Follow the directions and pour on the Bayer
2. Cover the ground with worm castings.

Any maybe, just maybe, I'll actually fertilize my plants this year instead of just thinking about it.

(And for now, I'm going to make sure the ground is totally cleared away of last year's ground debris and put down new mulch.)

I pray that is all that I need to do. I don't want a summer long war year after year. :-(
bermudakiller
Union Grove, AL

January 24, 2008
12:56 PM

Post #4446493

Sunlight oil is a petroleum based oil, known as paraffinic oil. Sold under several names, but sunlight is the only one available here., Ultrafine used to be offered as well Do a net search but also a price comparison as the prices vary widely but are fairly consistent at the big box home improvement stores. Buy several bottles if you find it as it sells out fast, keeps for years and is poorly restocked. One thing that is most important is contunued use till all eggs have hatched and have been killed before thay can lay again. Look up life cycle and see the time from hatch till the next generation, usually a week to 10 days is enough, but not always.

Rich, as i can't burn often, esp. in the current drought, I usually put insect ridden brush into plastic bags and seal till i can burn. I wanted to know if you had any better ideas?
Rich_dufresne
Candor, NC

January 24, 2008
3:30 PM

Post #4447048

bermudakiller, keep the material as far away from your plants as possible. Storing in a dark bag will probably cook the critters during hot summer storage, but the bags will get fragile and tatter readily from UV photodegradation.

For mulch, if you can't find worm castings, use hardwood bark mulch (not ground brush with lots of wood tissue or pine bark mulch), and dress the mulch with coffee grounds to provide nitrogen. There are three benefits to using grounds: worms love them, the nitrogen breaks down the mulch into ideal compost, and the leftover caffeine will probably deter ants and other pests.

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