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Plant Pests Series – Leaf Miner

By geekgardener, on January 3rd, 2012%

Hope you all had a great new year weekend.

Few weeks back, I posted a topic in the forum to build a database of pictures of various pests. The main idea was to make it easier for novice gardeners to identify the pest they are having without much difficulty. With that in mind, I started looking closely at my plants every single day; all the plants. I got plenty of insects. This inspired me to start this Plant Pests Series. Every post in this series will feature a pest. It will have the following about the pest

Identification
Damages
Control
- Natural
- Chemical

Introduction

The star of this post is Leaf Miner. Leaf miner is a name given for the larval stage of many insects that consume the leaf tissue. Most of the leaf miner are larval stages of flies. While the adult is considered harmless, the larvae feed on the upper and lower surfaces of the leaves causing the wavy squiggly lines on the leaf surfaces

Identification

In case of leaf miner, the pest can only be identified after the damage is done. The symptom of leaf miner damage is the squiggly lines made by the maggot as it bores through the leaf tissue eating it away. The damage will look like the picture below. (The damage via alphabets in the image is done by me..insects are innocent!)

Leaf miner damage

After several days of mining in the garden, I was able find a miner taking a walk in the park, munching along..The dark lines are its poop.

Leaf Miner Larva

This is up close with the maggot. The damage to the leaf is very clear in the picture below. The larva has eater away the leaf tissue and only the surface epidermis remains.

Leaf miner close up

Damage

Leaf miner attack can cause serious damage based on the density of the insects and the stage of the plants. Seedlings affected by leaf miner show stunted growth and might die but it is not very common. Plants with heavy foliage can handle some amount of leaf miner damage without any noticeable impact in yield. But heavy infestation can seriously reduce the yield.

Life cycle

This is how the story of a leaf miner goes..

Mature larvae in soil/host plants wait for the conducing weather. As the warm weather sets in, they go into pupal stage and turn into adults.
Females after mating, search for leaves in order to lay the eggs.
Females have a needle like organ which aides them to pierce the leaf and lay upto 200 eggs into the leaf tissue…under the surface.
From then, all it takes is couple of weeks for the eggs to start drawing lines in the leaves.
After 3 weeks, they become mature and is all set to go into pupal stage..
See Step 1.

Leaf miner Control

Usually leaf miners have lots of natural enemies that consume them. The outbreak of leaf miner might arise after a use of insecticides that kills its enemies too. The safest control is to simply remove the affected leaves and dispose them off.

Organic control

Neem oil is an excellent pesticide to control leaf miners. 30ml of neem oil in a litre of water along with little dish soap can be used as a spray.

Alternatively, one can use yellow sticky traps to attract these flies and destroy them.

Chemical control

Insecticides like permethrin, bifenthrin and deltamethrin can be used to control adults. Since these are contact insecticides the larvae inside the plants are still not affected.

To control the larvae systemic insecticides like Imidacloprid can be applied. Dosage of these insecticide are as per the instructions on the label.

That’s all in this post.

Happy gardening

Hydroponic/Soilless Cucumber Production in greenhouse – Part II

By geekgardener, on December 8th, 2011%

This article is a continuation of Part I of Hydroponic Cucumber production. The response to the previous article was amazing. Questions started pouring in in huge numbers. This shows how much interest people have in commercial hydroponics. I will try to keep these articles simple for a home gardener and at the same time, sticking to methodologies followed for a commercial production.

This last part dealt with seed starting, transplanting and training. This part will deal with crop management, irrigation, fertilization and harvest.

	Recap: These plants are about 40 days from the date of sowing. They are sown in black polythene bags filled with coco peat media. Each bag contains about 12 liters of media in it. If it is mini cucumbers, there can be 2 in a bag but for bigger English cucumbers one per bag is recommended.The spacing of the plants are at 16-18 inches apart.
	Pruning: Regular pruning results in healthy, sturdy plants that yield continuously. The fruits will also be of uniformly large size. Too many branches can dilute the vigor and when then number fruits goes higher than the plant can handle, it automatically aborts the next set of flowers till the current ones are harvested.At the same time, care should be taken It can be observed that there are flowers on all the nodes.
	Pollination: English cucumbers are parthenocarpic. It means, there is no need for pollination for the fruit set. This feature makes it a wonderful candidate for greenhouse growing. The grower need not worry about brining in bumble bees for pollination. Also, all the flowers are female flowers. As many flowers there are, that many cucumbers you will get( Well, Technically!).In the picture to the left, you can see the tender cucumbers growing vigorously. It takes 10-14 days for a cucumber to mature. It grows very fast especially in the last few days of that duration. The weight ranges from 400-550grams per cucumber. This weight depends on the stage of picking.
	Maturity: These cucumbers are approx 1 week old ( from the day of flowering). The ridges are a feature of the cucumber variety and they gradually become very shallow as the cucumber matures.The skin is very thin so care should be taken to immediately store them in a cool place or shrink wrap them. Otherwise, they can lose moisture too quickly and become soft and rubbery. On the left, is cucumber 2 days short of harvest. More you leave on the plant, more nutrients are diverted to the old cucumbers and this might delay new ones getting formed at the top. Always maintain a balance with respect to number of fruits per plant. 6-7 fruits at any point in time is a good number. More than that, one might experience deficiencies of calcium due to the inability to support more fruits.
	Training: The plants are allowed to reach the top overhead wire. Till it reaches that height, all the side shoots and branches are removed.Once it touches the overhead wire, the top is cut off and two branches are allowed to form. They are allowed to fall down from the top. Care should be taken such that the stem doesn’t break as it winds around the wire. The fruits are allowed to form on the laterals.These plants on the left have about few inches before their tops are cut off and are allowed to branch.
	Nutrients: Most of the questions, I received were related to this one topic. Nutrient! Nutrient! Nutrient. My idea was to write a dedicated post on Hydroponics Nutrients. Not just for Cucumber but for any crop. A subsection in a post will do no justice to the topic. So in this section I am just going to mention the ppm values used and deal with this topic in detail the next post. Macro Nutrients Nitrogen(NO3):190 Nitrogen(NH4):20 Phosphorous:50 Potassium:380 Calcium:190 Magnesium:50 Micronutrients: Fe:0.8, Mn:0.5,Zn:0.3,B:0.5, Cu:0.05, Mo:0.05
	Nutrients Continued: It is important to remember that the nutrient is only part of the equation. There is no one single nutrient for any crop. Plants tolerate a range of nutrients. It is the growers responsibility to read the plant and if necessary modify the nutrient to suit the environment. Regularly “read” the plant for deficiencies, toxicity, insect attack. If you find certain the plant is too vegetative( lush leaves, less/no fruits), then take certain measures to steer it into generative mode. There are lots of methods one can use to steer the plant towards vegetative or generative. Temperature, Irrigation duration/frequency, Electrical Conductivity(EC) are some of them.So one formula doesn’t suit all. It needs to be tailored to the area. In the coming posts, I will explain in detail about How to make hydroponic nutrients and how to modify it to suit the plants need. Also on how to “read” your plant.
	This is 1st Harvest. Each cucumber weighed 500-550 grams. We were very excited that we didn’t even eat these cucumber for couple of days.It was like ..in the song from “Damadamm” no touching no touching.. only seeing only seeing”). Most of them averaged and 14-15 inches but some of them dared 17inch mark. This was from one plant that was first to yield. It was also the one that had saw-dust mixed in along with cocopeat as a trial. I was impressed .
	2nd Harvest was huge. I picked about 20 cucumbers and what I liked about this crop was the uniformity. Every plant had almost same number of cucumbers on them and was quite a view in my greenhouse. One thing to remember with english cucumbers is that they have a very thin skin. If not stored properly, they lose water very quickly leading to a soft rubbery fruit. They remain crunchy for a long time if stored properly. The fruit is so juicy and crunchy without the seeds coming your way.
	3rd Harvest and again I got 20 cucumbers. At this point, we were loaded with cucumbers in our house and I already started selling this to my colleagues at work. Who doesn’t love vegetables delivered to their cubicles.. Parallely I had beefsteak tomatoes growing and their yield was pretty good as well. It was tomato and cucumber month. I had so much surplus that I approached nearby Vegetable supermarket and the push cart guys. To my surprise both of them agreed in a jiffy. The best part was I got to set the price and they were ready for it. They also said that they will take lettuce and other exotics I grew. So far, I have harvested around ~40 kg. The crop had its share of insects. I will handle insects and diseases to watch out for in cucumber production in my next post which is Part III.