In this tip:
In this post you’ll find a description of some plant diseases and insects that I saw in my garden. I added some photos. Info from internet and my own experience.
In early summer (June) it can happen that “many onion plants in your garden are ill”. See photos and descriptions below.
A1) Onion fly
Leaves of the onion plants are yellow – brown and lie on the garden soil.
In the onions there are maggots of the onion fly. Onion plants will die.
A2) Leaf-miner fly (on onion plants)
Leaves of the onion plants are green and curled.
In the onion you see “eating grooves” and maggots or brown pupae.
The onions will grow to big ones with deviating shape as shown on the photo above.
A3) Help against onion flies and/or leaf miner flies.
- Buy many onion sets (more then calulated).
- Plant only few onion sets in early spring (March and April). In these months, there is big risk of attack by leaf miner flies and/or onion flies.
- But……you can plant “many” onion sets in March and April (early spring) when you put a layer of hay on the soil between and around the small onion plants. Due to the layer of hay, the soil does not dry out so fast. And there is less attack by the onion flies and miner flies. See chapter A5).
- Plant most onion sets in mid spring (early May). The leaf miner flies are not active during that time. Putting hay around and between the small onion plants works well too; soil does not dry out fast.
- Harvest the onions in July to September (late summer, early fall). Onions are big enough then. Leaves get yellow and topple and the onions do not grow thicker anymore.
A4) Does it help?
The first row contains onion plants from onion sets that were planted in early spring (April). Many onion plants have been attacked by onion flies or leaf miner flies.
Two rows of onion plants from sets planted at mid spring (May 15). All onion plants look healty. At the end of August (late summer) they have grown into normal sized onions.
Conclusion: onion sets planted in May (mid spring) give a good harvest in August (late summer). And there is little attack by insects.
A5) A layer of hay around and between the onion plants:
When you have planted onion sets in early spring (March, April), you better lay some dry hay or mowed short grass between and around the little onion plants. The soil will not dry out so fast, the onion plants grow well and show less diseases and damage of onion flies or leaf miner flies.
You can always put dry hay on the soil between and around the onion plants. That works well always.
A6) Test: planting date and hay around.
To find out when onion flies or leaf miner flies lay their eggs on onion plants, the following experiment has been executed;
- At March 20, one onion set has been planted in the garden soil, in a small furrow. Each subsequent day, another onion set was planted in that furrow.
- At May 1, the 43th onion set was planted. The row was full then.
- From the beginning of April on, a thin layer of dry hay has been put around and between the onion plants that were visible. (My experience; there is less attack of flies when there is dry lawn grass (short hay) on the soil around the onions. Hay is for sale in a pet shop and not expensive.
- One year later, the experiment has been repeated with 3 rows of onion sets. In two rows there was dry hay between and around onion plants, in the other row there was dried grass or dry straw.
A6b) Results and conclusions:
- No (or little) attack by the leaf miner fly or onion fly observed.
- A few plants showed curled leaves, the harvested onions look normal.
- Harvest: 38 onions out of 43 sets and 115 onions out of 129 sets. Many big onions and a few small onions.
- Under the layer of hay (or straw), the soil does not dry out fast and the onion plants grow better (faster).
- Hay around onion plants works well against attack by onion fly and leaf miner fly, even during the “risk period” of the leaf miner fly (March and April).
- Hay around onions give more and bigger onions than dried grass or straw around onions.
- The last 6 planted onions in each row showed no attack by flies, no curled leaves and no vermin.
More and detailed info at chapter E)# of tip 5) Planting onions in a small furrow.
B1) Curled leaves
In early summer (June) some leek plants can have curled leaves. Similar to the curled leaves of the onions caused by the leaf miner fly.
There are no maggots or pupae. Only white eating grooves in the green leaves. As indicated between the 2 red arrows. This attack is caused by leaf miner flies.
Help against curled leaves:
- Do not plant out the leeks that have been attacked.
- Sow more leek seeds so you have more leeks to plant out later.
- Grow small leeks in your garden under a tunnel greenhouse with ultra fine mesh netting at both ends of the tunnel. Experiment spring 2019. Results not yet known.
B2) Purple spots on leaves
In autum, leaves of leek plants can look like this.
This disease is called purple blotch. The leaves have purple spots. The leaves have “dead ends”. After removing the coloured leaves, the plants are okay. Leek harvest is smaller.
Info on the internet, see this site
This disease occures after a cold and wet weather period. Maybe after planting leeks too deep or too much manure added.
The disease occured in my garden (for the very first time in more than 25 years) in 2012.
- Internet: Shallow planting. Adding less manure. Putting garden earth around the plants not until the plants are big.
- My experience: Put leek plants in round holes (diameter 6 cm, 2.4 inch) in the garden soil. Keep the holes “open” for a long time. This results in no risk or little risk of this disease.
B3) Brown pupae (leaf miner fly)
Brown pupae in leeks frequently occurs. Almost every veggie gardener has seen the brown “things” on and under the leafs of a leek. There are cracks and tears in the outer white leaves of a leek. The edges of the cracks are light brown. In this chapter you find an extensive description about this attack (and how to reduce this attack).
Typical for this disease (see photos above):
- Some (white) parts of the leek plant have long “cracks” or “tears” with light brown edges.
- Eating tracks are visible on leaves and white parts.
- Pupae hide in leaves or at other parts of the plant.
- Pupae are about 4 mm long (1/6 inch) and dark or light brown. On the lowest photo at the right you see a maggot (or small pupae) that is somewhat smaller.
- Sometimes there are some maggots on the leek. This maggot is still eating leek material. It is not yet ready to transform into a brown coloured pupa. The lowest photo with a wooden cocktail pick shows the size of the maggot.
These pupae and maggots are children of the “allium leaf miner flies” also called “leaf miner flies”. You can find info about this disease on the internet, for example on this site .
Leaf miner flies lay their eggs on the leaves of the leek plants in spring (early March to early May). Eggs –> white maggots –> brown puppae. The pupae “rest” until the end of summer. During this rest period, the pupae are in the leek plants (or somewhere else, such as in the garden soil or in leaves of leek or in compost).
So there are 2 periods when leaf miner flies lay their eggs on leeks; in spring and in late summer/early autumn.
Help against leaf miner flies
In spring and in late summer/early autumn, you have to prevent the leaf miner flies from laying eggs on the leeks;
- In spring you can sow or plant leek in a “flyproof” tunnel greenhouse and let hem grow bigger there.
- In late summer/early fall you can trim the leaves of the leeks. You can also lay dry hay on the trimmed hay plants.
Below an extended description of these 2 procedures.
- In spring; grow leek in a “flyproof” tunnel greenhouse
You can sow leeks indoors (e.g. in shove trays) at late fall to early winter (November, December). Replant the small thin long leek plants in the garden soil under a “flyproof” tunnel greenhouse, from late winter to early spring (March, April). Replant the leeks or shove blocks of soil with small leek plants on/in the garden soil. More info tip 18) .
Or sow leek in the garden soil under a “flyproof” tunnel from March (late winter) on.
Planting or sowing leek and using a “flyproof” tunnel is as follows;
- Put the tunnel greenhouse on the garden soil.
- Open the tunnel or remove it temporary.
- Sow or replant the leeks in planting beds that are about 5 centimeters (2 inch) lower than the garden soil level. That’s easy when watering; you can let water flow in the lowered planting beds. More info further in this chapter.
- Then put the tunnel greenhouse over the planting beds again. See 2 photos above; upper photo of April 1 (early spring), lower photo of April 28 (mid spring).
- The curtain material is at both sides of the end plate;
- This procedure is easy and less screws needed.
- At the outer side of the plate, the curtain holds the the insects (miner flies).
- At the inner side, the (soft) curtain material is pressed against the hard end of the bent corrugated plate. Thanks to the curtain material, the end plate seals better against the corrugated plate. There are very narrow openings (slits) between tunnel and end plate. The leek fly or leaf miner fly can not pass these slits.
- My end plates have 2 layers of curtain material over the air openings. My curtain material is well air permeable; you can easily blow air through 2 layers of curtain material.
When you have curtain material that is less permeable, you can cut one round hole in one layer of curtain material. This hole is right before and just as big as the air opening in the plate. Below a description.
Put this end plate with cut opening (in the curtain material) towards the tunnel. Now there is only one layer of curtain in the air opening. Still there is still soft curtain material against the side of the corrugated plate.
The above mentioned construction makes the tunnel greenhouse very airy, but still inaccessable (impassable) for leek flies, leaf miner flies and other insects.
Below a description of making the end plates.
- Drill 4 holes (diameter ) in the plate, next to the circle;
- Diameter of the holes is about 4 millimeters, 1/6 inch.
- Drill the holes at “3, 6, 9 and 12 o’clock”.
- Drill the holes next to (right at the inner side of) the circle.
- These holes are useful when sawing the round hole in the plate using a fret saw. The saw frame of the fret saw is too short to saw all circle round. In each hole you can turn the saw frame and “reverse the saw direction”.
- Use sand paper to polish the side of the round hole and the left side short edge of the plate (see photo above). Polish until there are no sharp edges or flakes.
- Drill 3 holes in the plate (needed for the fixing screws);
- Diameter of each hole is about 3 millimeters (1/8 inch).
- Distance between each hole and edge of the plate is about 10 centimeters (4 inch). See red arrows on photo above (3 photos back).
- Cut a piece of curtain material with the right dimensions.
- Fold the perpex plate “well fitting” in the curtain (as shown above).
- You can use 2 clamps to fix the corners of the curtain.
This photo shows an older design. The curtain material has been put crossways on the perspex plate. At one side, both ends of the curtain have been fixed using staples (stapling in this material was hard to do). Four (4) screws fix the curtain material to the perspex plate, one screw at each corner. This construction is harder to make than the construction described above.
- At each plant bed you can put a special “watering tube” in the soil.
- Use a funnel and beaker.
- You can fix a piece of curtain material around the exit of the funnel;
- Put the funnel on the watering tube.
- Pour water from the beaker into the funnel.
- During pouring, use one hand to keep the funnel in position.
- You can pour water in the elbow tube, without using the funnel, but then you have to take aim properly.
After May 15 (late spring) the leaf miner flie does not fly anymore. And does not lay eggs on leek plants (until August, end of summer). So it is time to open the greenhouse tunnel and to replant the leek plants. Check if the leeks have been attacked by the leaf miner fly; when attacked, the leaves are curling and deviating from normal.
- Five days after opening the tunnel, the leek plants have been taken out of the plant bed and put in the garden soil.
- The top of the leaves are still a little bent and light brown.
- After shortening the carrots and the leaves, the leeks look normal.
- All leaves of all plants look normal, so no attack by the leaf miner fly.
- There are many thick leeks, thicker than a pencil and a few plants that are thinner than a pencil.
On August 1 (mid summer), leeks have grown bigger.
From mid November (mid fall) on, leeks have been harvested.
On the photo above you see harvested leeks. There are 3 groups of leek. Under each group of leeks there is an indication; Nothing, Trimmed or Trimmed and hay on. Below an explanation of the groups. Click on the photo for wide screen.
- At the left side of the photo there are leeks that have grown “normally”; no trimming and no hay on (group “Nothing”).
- In the middle you see leeks that have been trimmed weekly (group “Trimmed”).
- At the right side there are leeks that have been trimmed weekly and that had hay on the trimmed leaves. (group “Trimmed and hay on”).
- At 6 leeks of the group “Nothing”, all pupae and maggots have been collected, see photo above. The 6 “Nothing” leeks contained 4 maggots and 10 pupae in total.
- You better crush the pupae and maggots (to prevent new flies from hatching).
Later on, more leeks of the group “Nothing” have been harvested and cleaned. See photos below.
Later on, 14 more leeks of the group “Trimmed” have been harvested and cleaned. These leeks are rather thin compared to the other leeks. See photos below.
One week later, 5 more leeks of the group “Trimmed and hay on” were harvested and cleaned. See photos below.
After winter storage
You can put a tunnel greenhouse of transparent corrugated plate over 1 row of leek plants, growing in the soil.
At some potatoes I see brown spots (warts).
After peeling the potatoe looks normal.
This can be caused by mixing (too much) agricultural lime through the garden earth. Potatoes grow well in slightly acidic soil.
Help: Do not add agricultural lime in the garden soil.
This disease is caused by larvas of the the cabbage gall midge. Info on the internet is here . This midge lays eggs on cabbage plants that grow at sheltered, calm places in the garden. My attacked cauliflowers grew next to the stake beans.
Plant the cabbages on windy places in the garden.
E1) Brown spot at lower side of tomato
Green or ripe tomatoes can have a brown spot at the lower side (opposite the crown). This is called blossom end rot and is caused by water shortage. The tomato plant is not ill, so keep the plant in the soil. You can throw the tomato in a compost container or cut away the brown material.
Add a little water to the plants dayly. Better add 1 small beaker of water each day than much water once a week.
E2) Crack in tomato
When much rain water falls on the tomato plants and/or when you water the tomatoes too much, you can get tomatoes with cracks.
Tomatoes on the plants can get cracks even before they are ripe.
When you add a little water to the tomato plant each day (at dry weather), there is less risk of cracks in the tomatoes. Watering goes well when using a bucket and a small beaker. You better pour 1 small beaker of water at each plant daily. That’s better than adding a big amount of water once a week.
E3) Dark spots on fruits, stems and leaves
It is possible that you get brown coloured tomatoes and brown leaves at the plants. This plant disease is called Phytophtora.
It is probably caused by rainy weather during late summer, early autumn (August, September). Cold rain water on the plants and fruits causes the plants and tomatoes to get brown (or rot).
Below some photos:
Tomatoes under a roof in my backyard garden at early autumn (September 1). As you see there are a lot of “good-looking” healthy tomatoes. I counted more than 100 tomatoes hanging on 11 plants. Only 10 tomatoes hanging under the roof have brown spots. And some plants have leaves with brown spots.
When there is no roof over the tomato plants, tomatoes can get brown spots and rot during “a rainy summer and a rainy, cold autumn”.
Tomatoes in my allotment garden. Under the roof there is plastic foil to catch dew drops, so they do not fall on the tomato plants.
At dry weather the side foil is folded down.
During heavy rain the side foil is fixed to the roof.
With side foil fixed, the roof is still airy thanks to openings above and below the side foil.
F)# Witloof (Chicory)
These witloof heads don’t look healty. There are brown, sticky, short outer leaves. On the heads you see spots.
This witloof has grown on chicory roots with non removed outer leaves. Maybe the compost in the flower pot was too moist during witloof forcing too.
The left side photo shows the chicory roots before witloof forcing. On the right side photo you see chicory roots with brown short outer leaves right after breaking off the heads.
Always cut or break away the outer leaves of chicory roots before forcing witloof heads. More info in chapter N2) of tip 24) Growing chicory .
Winter carrots can have deep cracks.
- Regularly water the garden soil around the carrots.
- Lay hay or straw around the plants on the soil; the garden soil does not dry out fast.
Preparing for a meal:
You don’t have to throw these carrots on the compost heap.
Use a kitchen knife to cut the cracked carrot in good pieces. Prepare the pieces of winter carrot in the kitchen.