Saturday, April 16, 2016
Sunday, April 10, 2016
Q. A few days ago my rose bushes were swarmed with small black (iridescent) flying beetles and they've cleaned out most of my roses. They also wiped out my one strawberry plant.
|Flea beetle ataxic grape leaves leaving holes|
|Flea beetles aren't very large but they are small, black and iridescent|
|If enough of them come through this is the kind of damage they can do in a short time|
A. I have not seen them but flea beetles come to mind this time of year. They are small, black and iridescent. This is the time of year they are normally active as well again in the fall.
They normally come in large swarms devouring a lot of soft leaves including roses, strawberries, grapes to name a few.
In about two weeks they will be gone as quickly as they appeared. The plants will grow back. I would not recommend anything to spray but simply wait until they are gone then give the plants a deep watering and fertilizer so they recover quickly.
The rain this past weekend may have brought some problems along with it, the same as it did last year after a rain like this. Problems might develop during the coming week or, with some plants, even extend into May or later.
|Japanese euonymous with powdery mildew|
Plants like roses may show signs of powdery mildew disease. This disease is aggravated by cool, wet weather, splashing rain, followed by warm weather. It appears as a white powdery dust on the leaves that can kill them. This disease is usually weak in our climate mostly because of our low humidity and cloudless days.
|Rose with powdery mildew|
Pull off a few leaves so air can circulate through the plants and allow them dry out naturally. Apply a preventive spray of a conventional fungicide for roses, sulfur dust or Neem oil. Lower humidity, air movement and sunlight in the coming days may clear up this problem without pesticides on some plants.
|Fire blight in pear|
Another problem on European and Asian pear as well as some apples is fire blight. This disease is particularly virulent too many members of the Rose family such as many of our fruit trees.
If these trees were flowering during this rain it is possible this disease may show its ugly head toward the beginning of May. Look for jet black dieback on new growth, usually very close to the infected flowers.
|Classic symptoms of fire blight in pear|
Cut out these stems or branches 12 inches below the infection and sterilize pruning tools after each cut. Bag these infected plant parts and get them off of your property.
|Pomegranate disease due to wet spring weather|
Pomegranates that are flowering may develop fruit with a black interior later in the season. This disease can be the result of wet weather when they are flowering. This disease may not appear on fruit until quite a bit later in the season. It does not spread beyond the fruit and the fruit is inedible.
|Mushrooms popping up in wood mulch after rain|
Mushrooms frequently pop out of the ground after a rain like this. Nothing to worry about but knock them over with a rake and keep them away from your pets. They are feeding off of decaying wood or wood chips in the soil or on the soil surface. They are good guys.
Q. My lilacs have bloomed and the flowers are gone. Is now the time to prune or do nothing? How do you prune or care for the lilacs.
|Lilac planted in rock mulch with brown scorched leaves|
A. Most people don't know that low-chill varieties of common lilac will grow here as well as the Persian lilacs. Plant them in plenty of sunlight but in places which avoid the hot afternoon sun. All lilacs must be planted in a composted soil with a wood chip mulch. Rock mulch will not work.
Low-chill varieties do not need as much low temperatures to produce flowers. Lilacs that are not low chill will not produce as many flowers in our warm winter climate. Some plants require long periods of time when temperatures are cold so that flowers will be produced the next year.
Persian lilac may be a better choice for our climate and in smaller yards than common lilac. Persian lilacs are smaller in stature than common lilac, with smaller flower clusters and a lower winter chill requirement.
Hopefully local nurseries and garden centers that sell lilacs for our climate are selecting low-chill types such as an old time favorite here called "Lavender Lady". I believe this, along with "Angel White" were the first low chill lilacs available that would grow in the desert Southwest. Many of these low-chill varieties are referred to as the “Descanso Hybrids”.
Lilacs are not desert plants so they require lots of compost mixed in the soil at the time of planting with the soil covered in wood chips that decay over time. They should not be in rock mulch.
A very nice article appeared in Sunset Magazine and you can read it here http://www.sunset.com/garden/flowers-plants/mild-climate-lilacs
As with any seasonal flowering shrub or tree the best time to prune them is soon after flowering. If pruned later than this, the flowers for next year may not be produced.
First, remove the dead flowers before they form seeds by cutting them off at the base. Next, if needed, cut back branches or stems.
To increase the number of flowers you should increase the number of new branches it produces. Use a "heading cut". This type of cut is made somewhere along the length of the branch, usually just above a leaf on the outside of the branch.
Heading cuts grow three or four new shoots for every one that is cut that is made. This is an excellent way to make a shrub denser with more flowers.
If the shrub is getting too large, remove one third of all the longest stems back to within a couple of inches above ground. New stems will grow from just below these cuts.
A radical way of pruning this plant is to totally cut it off just above the soil surface. With plenty of water and some fertilizer new shoots will grow from these very short stubs resulting in an all-new plant. This is pretty radical but if the plant is overgrown with lots of wood showing, this may be your only alternative.
Remember, after pruning give it plenty of water and fertilize it with an all-purpose fertilizer.
Q. Two out of my 3 bottle brush bushes look dry and yellowish. The first 2 years they were fine. Does it mean they are not watered enough?
|Bottlebrush after Winter cold damage|
|Bottlebrush with yellowing due to iron chlorosis|
A. Many plants in general, including bottlebrush, can be damaged if watered either too often or not watered frequently enough. If you are going to error about watering, it is better to give plants too much water than water them too often. But I think the problems iron, not water.
Right now water plants like this once or maybe twice each week at the most. Yellowing of the leaves can also happen because of real low winter temperatures. Similarly, it can also happen if the soil is not improved or covered in rock mulch.
Bottlebrush don't like rock mulch at all and if they are planted in rock mulch they frequently turn yellow in 3 to 5 years. If they get yellow enough, the leaves begin to turn brown and scorch. This is what I think happened to your plants.
Purchase an iron fertilizer and apply it to the soil above the roots now and water it in. The best iron fertilizer contains the letters EDDHA on the label or in the ingredients. EDDHA iron chelate is an important for iron product to use in desert soils.
Iron applied to the soil will only improve the green color of new growth. The older leaves which are yellow can only be improved with an iron fertilizer solution sprayed on the leaves. Spray this solution in one week intervals until you get a dark green color.
If these are growing in rock mulch, buy good quality compost, not a soil mix, and spread it around each of the plants and water it in. Apply around one to one half cubic foot of compost to the base of these plants and water it in, even in rock mulch.