A Detailed Guide to Controlling Common Pests and Diseases of Photinia × fraseri (Red Robin)

Photinia × fraseri (Red Robin) has fairly strong resistance, but if it is managed improperly or the nursery environment is poor, gray mold, leaf spot, or damage from scale insects, cutworms and the like may occur. As a member of Yuanlin China Network, I would like to share some of my experience with fellow flower lovers, and I hope we can all exchange and learn more.

First, identify which pest or disease it is:

1. For gray mold, spray 50% carbendazim at 1000 times dilution as a preventive measure; during the outbreak period, spray 50% zineb at 800 times dilution for control.

2. For leaf spot, use 60% carbendazim at 300—400 times dilution or thiophanate at 300—400 times dilution for control.

3. For scale insects, spray dimethoate emulsifiable concentrate at 200 times dilution or at 800—1000 times dilution for control.

4. Control of cutworms should be carried out before planting; the soil should be deeply plowed as appropriate, and phosphorus-containing insecticides such as Tuchong Bisha should be spread.

Precautions

If cutworm damage occurs after planting, remedial treatment must be carried out promptly; otherwise, once it spreads, the damage will be severe, especially to Photinia × fraseri seedlings, and may cause death over a large area.

Common Pests and Diseases of Photinia × fraseri

Common pests and diseases of Photinia × fraseri:

1. Cutworm

   This mainly affects Photinia × fraseri in its seedling stage. Cutworms tend to breed in places near decaying plant matter, such as firewood piles, straw stacks, and livestock sheds in rural areas. The main damage caused by cutworms is their gnawing on the roots of Photinia × fraseri. If you find that many seedlings that were growing normally suddenly collapse or wilt, you can pull up the seedlings and check the roots. If there are obvious signs of pest gnawing, it is very likely a cutworm infestation. You can dig into the nearby soil, and cutworms can generally be caught.

   There are many ways to eliminate cutworms. Applying cutworm insecticide as a soil dressing or spraying a liquid insecticide can achieve obvious control results. Cutworm control must be timely, and the insecticidal effect must be monitored; if it is not thorough, another round of insecticide is needed.

2. Stinging caterpillar

   The name may vary from place to place. When human skin comes into contact with it, there is an obvious stinging pain. This insect mainly appears at the turn of spring and summer. If it is not controlled in time, the infestation can continue into autumn. It causes the leaves of Photinia × fraseri to be eaten over a large area, causing serious harm to the growth of Photinia × fraseri.

   The control method is mainly phosphorus-containing insecticides. The whole field needs to be sprayed, and the effect is generally very obvious. After the insecticide is sprayed, most of the stinging caterpillars will die. If the pest is eliminated thoroughly, only one application is needed per year.

3. Stem borer

   This name is not necessarily accurate either. The symptoms of this pest and disease are: boreholes appear in the trunk, and a lot of wood dust falls onto the soil below the trunk. This pest and disease generally occurs on large Photinia × fraseri trees more than 3 years old. The older the tree, the higher the incidence rate. If it is not treated, the tree will be hollowed out and break off.

   The control method is also mainly phosphorus-containing insecticides. A syringe can be used to inject diluted insecticide into the boreholes. When applying pesticide to the leaves normally, the trunk can also be sprayed appropriately to increase the control effect.

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Cultivation Techniques and Pest and Disease Control Knowledge for Container-Grown Photinia × fraseri

With the development of container nurseries, the advantages of container-grown plants are becoming increasingly apparent. To facilitate promotion and sales, new and superior colored-leaf tree species are increasingly being cultivated in container form. As a new and superior colored-leaf tree species, Photinia × fraseri is being accepted by more and more nursery producers, and the container cultivation form is gradually being adopted as well.

I. Seedling selection:

Photinia × fraseri is mainly propagated by cuttings. The seedlings available for selection include field-planted cutting seedlings, container cutting seedlings, and tissue-cultured seedlings. If a producer is just starting container production of Photinia × fraseri, it is recommended to introduce container cutting seedlings, that is, plug seedlings or tissue-cultured seedlings, to ensure the survival rate of the seedlings. Of course, field-planted cutting seedlings can also be used, or container cultivation can be carried out after the field-planted cutting seedlings have grown to the point just before sale.

II. Container selection:

For producers of container-grown Photinia × fraseri, container selection is very important. Different containers should be selected according to different specifications of seedlings and different cultivation purposes. There are many varieties and specifications of containers on the market at present. If long-term planting is considered, woody planting containers such as gallon pots can be chosen; their service life can reach about 3 years, they are anti-aging, and they can be reused, making them the first choice for cultivation. If short-term sales are considered, woody planting bags can be chosen; their service life is about 1 year, and the cost is relatively low.

III. Medium:

An ideal container cultivation medium should have 50% solids, 25% air, and 25% water. There are many materials that can be used as medium, such as fine sand, peat, perlite, pumice, pine bark, nuclear bark, coconut coir, sawdust, straw, rice husk, carbonized rice husk, and sugarcane bagasse. Specifically, the mixed medium should meet the following requirements:

(1) Good air permeability and drainage, while also having strong water-holding capacity;

(2) pH between 5.5 and 6.5, low EC, sufficient cation exchange capacity, and the ability to continuously supply the elements needed for plant growth;

(3) Consistent material selection standards, with no toxic or harmful substances and no pathogens, pests, or weed seeds, etc.

When mixing the cultivation medium, consideration should also be given to using as few medium material combinations as possible, possibly adjusting the pH, and adding long-acting controlled-release fertilizer. In production, considering factors such as cost and medium sources, peat and perlite are mostly used as the main medium materials.

IV. Potting small seedlings:

For container-grown small Photinia × fraseri seedlings, the cultivation medium uses peat:perlite = 4:1. When using it, hydrated lime should be added to adjust the pH and supplement the medium's calcium nutrition (because peat is all acidic and lacks calcium). When potting, several points must be noted: the root system should spread out, the seedling should stand upright, and it should not be planted too deep; generally, burying the rooting part 2 to 3 cm into the medium is sufficient.

V. Fertilizer use during the small seedling stage:

The most convenient thing in container seedling production is the use of long-acting slow-release fertilizer, which has a long fertilizer effect period; when using it, you only need to add an appropriate amount when mixing the medium. After the container small seedlings are planted, slow-release fertilizer can be applied, and water-soluble fertilizer can also be used for irrigation.

In container seedling production, peat and perlite are often used as the medium, which lacks Ca, Mg, and trace elements. Therefore, in addition to using controlled-release fertilizer as the base, water-soluble fertilizer also needs to be supplemented to quickly and effectively supplement the various trace elements necessary for seedling growth, so that the seedlings grow robustly.

VI. Repotting:

When the root system of container-grown Photinia × fraseri has filled the container, and when the pot is removed you can see that the fibrous roots have wrapped around the peat and water is difficult to soak through, it is time to repot. Key points for repotting: add 1/3 medium to an empty pot (apply base fertilizer, mix evenly), place the seedling in the center of the pot, straighten it, fill with medium, press slightly around the edges, and shake it a little.

The container used for repotting must be larger than the original one. Pine bark or nuclear bark medium and sandy loam soil free of weed seeds can be added to the medium to reduce costs.

Recycled medium must be disinfected before reuse (use Didike at 600 to 800 times dilution or other disinfection methods).

When applying base fertilizer during repotting of seedlings, the most convenient and economical option is to use long-acting slow-release fertilizer; you only need to add an appropriate amount when mixing the medium. The amount of fertilizer applied depends on the container size.

Taking advantage of repotting, you can straighten the poor growth direction of small seedlings and make them grow toward the shape we want.

After repotting, the container seedlings should be placed neatly, with the same number placed in each plot, and walkways should be left to facilitate watering, fertilizing, and other operations.

VII. Management:

The space inside the container is limited, and the amount of water and fertilizer it holds is very limited. To make container seedlings grow robustly, the medium in the container needs to be regularly supplemented with water and fertilizer. Watering is a frequent and meticulous management procedure. Usually, large containers are watered once every 1 to 2 weeks, and small containers also need to be watered once every 3 to 6 days. Of course, the watering frequency is also closely related to the size of the seedlings growing in the container. Uneven watering will cause the seedlings to lose water and wilt. Only thorough watering can make potted seedlings grow robustly. Under normal circumstances, when the peat in the upper 1/3 of the medium in the container turns white, it needs watering again; do not wait until the seedlings wilt to water. In particular, it should be remembered that after seedlings wilt, at first only a small amount of water should be applied to moisten the medium, and only after the wilted leaves of the seedlings return to normal can thorough watering be done. Never flood the pot all at once, otherwise the root system is likely to be submerged in water and rot, causing the death of the seedlings. If watering is very difficult to soak through, that is because the medium is too dry or the root system has tightly coiled around the medium. In management, the watering cycle can be shortened, or sprinkler irrigation equipment can be used for regular watering.

Topdressing is a very important operation for the production of container-grown Photinia × fraseri. The limited root growth space and frequent watering make the fertilizer-loving Photinia × fraseri appear nutritionally deficient. However, frequent use of quick-acting fertilizers not only easily causes fertilizer burn to seedlings, but also increases the production management cost and management difficulty of container seedlings. Therefore, we strongly recommend that container seedling producers use Apex long-acting controlled-release fertilizer; it only needs to be applied 1 to 2 times a year, greatly saving labor. When topdressing, hole application can be used, that is, inserting holes and applying the fertilizer into the holes. The number of holes per pot depends on the container size.

VIII. Pest and disease control:

The main diseases of container-grown Photinia × fraseri are anthracnose, leaf spot, etc. Control: during the outbreak period, use spraying for control. The selected agents include 50% carbendazim at 500 times dilution, 75% chlorothalonil at 500 to 800 times dilution, and 50% thiophanate wettable powder at 800 to 1000 times dilution. Spray once every 7 to 10 days for 3 to 4 consecutive times. For root diseases, Didike at 800 to 1000 times dilution can be used to drench the roots. Usually after pruning, pesticide should be sprayed promptly to prevent wound infection.

The main insect pests are aphids, moth larvae, etc. Use periodic spraying for control. Select imidacloprid at 800 times dilution, 90% trichlorfon at 1000 times dilution, or 50% fenitrothion at 1000 times dilution, or pyrethroid insecticides. The nursery should be inspected frequently, and pesticide should be sprayed promptly when newly hatched larvae are found.