Eng. SÎRBU CAMELIA MARIA (ALĂMOREAN) Ph D THESIS ...

UNIVERSITY OF AGRICULTURAL SCIENCES AND 

VETERINARY MEDICINE 

CLUJ -NAPOCA 

AGRICULTURE FACULTY 

Eng. SÎRBU CAMELIA MARIA (ALĂMOREAN) 

Ph D THESIS 

ABSTRACT 

RESEARCH REGARDING POTATO 

CULTIVATION IN THE BIOLOGICAL 

(ORGANIC) AGRICULTURE SYSTEM 

SCIENTIFIC COORDINATOR 

Univ.prof. dr. eng. GAVRILĂ MORAR 

CLUJ-NAPOCA 

2011

Ing. Camelia Maria Sîrbu (Alămorean) Abstract 

INTRODUCTION 

The potato, with a long and glorious history, is originally from Central and South 

America, where, along with corn, was one of the staple crops, which fed and sustained a 

thriving civilization and a stunning indigenous culture and assured the greatness of the 

Inca Empire. After the discovering of ”The New World” in the years 1492-1496, the 

potato arrived in the ”old Europe” around the year 1553, as an unknown plant, and later, 

managed to conquer the entire civilization. 

Besides wheat, maize and rice crops, the potato is widespread worldwide. The 

potato became a staple food for nearly all mankind, being used and appreciated not only 

in poor countries and areas in Asia, Africa and Latin America but also in rich and 

developed countries such as England, Holland, Germany, France U.S. and others 

(IANOSI I.S., 2002). 

Under the auspices of large international organizations such as UN or FAO, on 

December 22nd , 2005, the year 2008 was declared International Year of the Potato, and 

the importance of the potato in the world economics is also shown by the fact that this 

plant is the only agricultural crop traded at the Stock Exchange on Wall Street in New 

York. 

The potato is a crop with high production potential, an equivalent area being able 

to produce 10-15 times more food than wheat, corn or rice. 

Due to the high nutritional value of potato tubers caused by the balanced content 

of carbohydrates, protein, fat and vitamins, to their taste and high digestibility, the potato 

satisfies most tastes and most diverse requirements. 

The potato tuber is an almost complete food, with a high content of carbohydrates 

(15-25%, depending on variety), protein substances and vitamins (A1, B1, B2, B3, K and 

especially vitamin C, which summarizes 13-23 mg/100 g dry matter), and minerals (100 

grams boiled tubers contain 0.5 to 2 mg assimilable iron, assimilable phosphorus 25-50 

mg and 6-17 mg assimilable calcium) (WIRTHS, 1968 cited by DRAICA C . et al. 

1996). 

For industry, the potato is used in producing alcohol, starch and glucose. From 

1000 kg of potatoes one can get 56-132 litres of alcohol or 140 kg of starch, or 240-260 

kg of chips, or 700-750 kg of pommes-frites. Starch can be used for producing more than 

1


700 derivatives that be used in the food, pharmaceutical, textile industries, paper 

production, etc. (DRAICA C., 1995). 

Also, the potato is used to produce bioethanol which, blended with gasoline, is 

considered to be the fuel of the 21st century. Starting with 2017, the European Union 

plans to subsidize 50% of the petrol refineries that use a mixture of gasoline and bio- 

ethanol made of potato or other plants such as beets and maize (http://www.zdd.ro ). 

For animals, the potato is considered valuable fodder, providing 26-30 UN/100g 

respectively 0.64 to 1.50digestible protein/ 100g. A quantity of 4 kg boiled potato is 

equivalent to 1 kg of barley, 0.9 kg of corn or 12 litres of whey (Ianosi IS, 2002). 

In agronomic terms, the potato fits very well in grain or vegetable rotation crops, 

which need mandatorily, as part of the rotation system, a plant which develops its yield in 

the soil, which breaks up the soil this way and improves its physical, chemical and 

biological characteristics by its own growth and development in the soil . 

The coordination of this scientific research, the interpretation of results and the 

drafting of this paper were conducted under the direction of the distinguished university 

professor PhD Morar Gavrila. To him I address my most sincere gratitude and thanks for 

the support granted to my permanent professional and moral development. 

I express my gratitude and sincere thanks to PhD professor engineer Ion Oltean for 

his support in the establishment and completion of the Colorado beetle control 

experiments. 

I have to address my words of thanks and consideration to the team of the 

Phytotechny Department for their support during the preparation of the thesis. 

I also want to thank my family for the dedication and support throughout the 

preparation of this work. 

2


CHAPTER I 

THE CONCEPT OF BIOLOGICAL (ORGANIC) AGRICULTURE AND ITS 

EVOLUTION 

Chapter I presents the causes that led to the emergence and spreading of the 

concept of biological (organic) agriculture in Europe and worldwide, the concept of 

organic agriculture and the situation of organic farming in the world and in Romania. 

CHAPTER II 

THE CURRENT STAGE OF RESEARCH ON ORGANIC POTATO 

PRODUCTION SYSTEM 

The chapter presents the current stage in the research on the biological potato 

production system and describes the potato cultivation technology in this system of 

agriculture (conversion of land, location of the potato crop, crop rotation and soil tillage, 

soil preparation for planting and potato planting, fertilization and maintenance works, 

harvesting and storage of the potato yield). 

CHAPTER III 

RESEARCH OBJECTIVES, MATERIAL AND METHOD 

3.1. RESEARCH OBJECTIVES 

The research objectives were: 

� The study of a range of potato varieties suitable to organic farming, and 

which should be characterized by: 

- genetic resistance to major potato diseases; 

- resistance to degeneration, known resistance to major potato viruses; 

- a reasonable production potential, able to ensure economic efficiency; 

- accepted by consumers. 

� Identification of natural fertilizers applied at the soil or foliage level to help 

stimulate the photosynthetic efficiency and production; 

� Identification and testing of natural products to control pests and diseases or 

other natural control products accepted in organic farming; 

� Control of weeds through various means other than chemical 

3


3.2. MATERIAL AND RESEARCH METHOD 

3.2.1. Biological material used 

For studying the suitability of potato varieties to organic farming, an assortment of 

11 varieties were considered, varieties that had been created at the Romanian National 

Institute of Research and Development for Potato and Sugar Beet, Brasov or at other 

research stations around the country, such as those in Targu Secuiesc and Miercurea 

Ciuc; two varieties were of Dutch origin. 

These cultivars were as follows: Roclas, Zamolxis(Dacia), Cumidava(Amelia), 

Christian, Redsec, Productiv, Tentant, Frumoasa, Robusta, Rozal, Sante, Riviera and 

Agata 

3.2.2. Materials used in research 

3.2.2.1. Foliar fertilizers 

Of all the foliar fertilizers allowed in organic farming, the following products were 

used, in concentrations recommended by the producing companies: Biome PLUSS, 

Biostar, Maxiroot, Terra Sorb, Glutaxin. The foliar fertilizers were applied at full plant 

growth (June, July, August), 3 times each year. 

3.2.2.2. Potato blight control 

For the potato blight control, nine natural products were tested in 2004, and 7in 

the next year; all products are allowed in organic farming. 

The treatments were applied at full plant growth, twice in 2004 and 3 times in the 

following year. 

The treatments with natural products allowed in organic farming demonstrate the 

possibility to extend the foliage vegetation period beyond the natural resistance limit of 

the variety. The products we used were: nutritive clay, whey, Bordeaux mixture, 

bentonite, copper oxychloride, milk without fat, copper hydroxide, clay, potassium 

permanganate. 

4


3.2.2.3. Colorado potato beetle control 

In 2004, in the experimental field of the Phytotechny Department, located on the 

Cojocna farm, two natural extracts were tested, namely those obtained from Taraxacum 

officinale L (dandelion) and Tagetes erecta L, with a view to analysing their repellent 

effect upon the adults belonging to the Leptinotarsa decemlineata Say species. 

For the extract obtained from Tagetes erecta L., we used powder of flowers and 

receptacles in a percentage of 20% active ingredients with the following solvents: 

propylene glycol, ethanol, ethyl acetate and water with a ratio of 1: 0.15: 0.5: 8 . 

For the second extract, the one from Taraxacum officinale L, we used a tincture 

made of fresh leaves with 20% active ingredients, and, as solvents, propylene glycol and 

water with a ratio of 1: 1. 

To test the repellent effect of these extracts, they were tested either separately 

(checking two concentrations for each extract) or mixed (checking two mixtures with 

different amounts of extract). 

The Solo 4 Pump was used for the treatment, applying a normal volume of 

solution (800 litres solution / ha), so that the applied solution would ensure full coverage 

of the foliar system. The effectiveness was assessed by counting the egg deposits for each 

variant and reporting the number to the number of treated plants. Efficacy was calculated 

using the following formula: E% = (1-n / N) x 100 where n = average number of egg 

deposits / treated and N = average number of egg deposits/control plants (no treatment). 

Also in 2004, different hydro-alcoholic extracts were tested in Colorado beetle 

larvae control. In obtaining the extracts 12 species of plants were used: 

� Armoracia rusticana Lam. 

� Artemisia abrotanum L. 

� Artemisia capilaris, Artemisia absinthium L. 

� Chrysanthemum cinerariaefolium Trev. 

� Chrysanthemum balsamita var. canfora, 

� Leuzea carth. 

� Marrubium vulgaris L. 

� Mentha piperita L. 

� Nepeta cataria var. citriodora 

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� Ruta corsica L. 

� Taraxacum officinale L.; 

� Tagetes erecta L. 

For the extracts obtained from Tagetes erecta L., tested in 4 variants, we used 

powder of flowers and receptacles in a percentage of 20% active ingredients with the 

following solvents: propylene glycol, ethanol, ethyl acetate and water with a ratio of 1: 

0.15: 0.5: 8 . 

In other 4 variants we used an extract of fresh leaves of Taraxacum officinale 

L.,20% active ingredients, and as solvents, : propylene glycol and water, with a ratio of 

1 : 1. 

For 2 variants we used an extract of fresh leaves of Tagetes erecta, and as 

solvents, propylene glycol and water, with a ratio of 1 : 1. 

For other 20 variants, the extracts were made of herba (for each species), in a 

mixture of propylene glycol and water, with a ratio of 1 : 1. 

To assess the efficacy, the same method of calculation was applied, as the one 

used for repellents. 

In 2005 there were seven variants of vegetal extracts tested to determine their 

effectiveness on larvae of Colorado beetle. These were: 

V1 – extract of Armoracia rusticana , ratio 1:3 

V2- extract of Chysanthemum cinerariaefolium , ratio 1:3 

V3 - extract ofArtemisia abrotanum, ratio 1:3 

V4 - extract of Artemisia capilaris, ratio 1:3 

V5 - extract of Chysanthemum balsamita var. canfora, ratio 1:3 

V6 - extract of Marrubium vulgaris, ratio 1:3 

V7 - extract of Ruta corsica , ratio 1:3 

For further studies of Coloroado beetle control, a lab experiment was established 

for testing the three extracts of the most effective products on larvae of different ages. 

The extracts used were as follows: 

Extract 1 – Artemisia abrothanum – 9% in ethanol 20% 

Extract 2 – Chrysanthemum cinerariaefolium - 9% in ethanol 20% 

Extract 3 – Chrysanthemum balsamita - 9% in ethanol 20% 

6


Extract 4 – Armoracia rusticana 

3.2.3. Research methods 

a) The influence of foliar fertilizers and biological products used to control blight on 

potato yields in varieties suitable for organic farming 

In 2004, foliar fertilizers were applied to the 12 varieties. Also all natural products 

tested for blight control were applied to the 12 varieties. 

In 2006, 2007, 2008 we initiated systematic trifactorial research on the interaction 

between variety, various blight control products and foliar fertilizers respectively. 

Experiments have been located and calculated by the method of subdivided trials with 2 

and 3 factors, in four repetitions. 

Experiment 1. – The influence of foliar fertilizer on the yield in potato varieties 

suitable for organic farming with the following factors and graduations: 

Factor A- Experimental year, with three graduations: 

a1 - 2006 

a2 – 2007 

a3 - 2008 

Factor B – Potato cultivar suitable for organic farming, with five graduations: 

b1 – Robusta 

b2 – Rozal 

b3 – Redsec 

b4 – Amelia 

b5 - Productiv 

Factor C – Foliar fertilization, with six graduations 

c1 – no fertilizer 

c2 – Biomit pluss 

c3 – Biostar 

c4 – Maxiroot 

c5 – Terra Sorb 

c6 – Glutaxin 

7


Experiment 2. – Blight control using biological products, with the following factors 

and graduations: 

Factor A – Potato cultivar suitable for organic farming, with five graduations: 

a1 – Robusta 

a2 – Rozal 

a3 – Redsec 

a4 – Amelia 

a5 - Productiv 

Factor B – Alternative products for blight control, with eight graduations: 

b1- no tratament 

b2 – Bordeaux mixture 

b3 – clay 

b4 – bentonite 

b5 – copper oxy-chloride 

b6 – copper hydroxide 

b7 – nutritive clay 

b8 – potassium permanganate 

The experiments were placed in 4 repetitions rigorously respecting the potato 

cultivation technology to highlight the experimental factors l. 

Blight resistance was assessed by the degree of attack of the disease on the foliage, 

given by the relationship between the attack intensity and the frequency of the disease. 

The assessment of the resistance of potato varieties to blight was done by hand marks 

from 1 to 9 (score 1 - very resistant to blight attack and score 9 - very sensitive). 

b) Weed control 

Out of the usual methods for weed control in organic farming, we chose to use fire. 

The reason was the emergence of weeds in the potato crop before the emergence of the 

plants, when the fire can act over the entire surface; after the emergence of potato plants, 

they can be protected with special shields, and the fire will be conducted among them . 

8


Fig. 6. Weed control(original) 

We used a special tool made in the workshops of the university, designed by our 

team, and consisting of a cart on bicycle wheels that can move around the field directing 

a jet of gas from a tank located on the trolley. Weeds were observed and destroyed at 

various stages of development and the fire was controlled by adjusting the jet to cover the 

surface between the potato plants (Fig. 6).. 

9


CHAPTER IV 

SOIL AND CLIMATIC CONDITIONS UNDER WHICH EXPERIENCES 

WERE CARRIED OUT 

4.1. EXPERIMENTS LOCATION 

Over the years, experiments have been conducted in several locations: in 2004 in 

the experimental fields of USAMV Cluj-Napoca from Cojocna farm, and the in the 

experimental years 2006-2008 at the Research Station for the Culture and Development 

of Pastures- Jucu. 

Subsections 4.2, 4.3. and 4.4.present the soil and climatic conditions in which the 

experiments were conducted. 

CHAPTER V 

RESULTS 

5.1. RESULTS REGARDING THE SUITABILITY OF THE STUDIED CULTIVAR 

ASSORTMENT TO BIOLOGICAL AGRICULTURE 

5.1.1. The results regarding the suitability of a potato cultivar assortment to 

biological agriculture, in 2004, in Cojocna, Cluj county 

The main features studied for the varieties considered in this research were: total 

yield, the average weight of a tuber, the average number of tubers in a nest and the 

resistance to blight. In the first year (2004) a number of 12 varieties of potato were 

studied. 

The Romanian varieties most suitable for organic farming, in the experimental 

year 2004, were Robusta, Redsec, Rozalia and Amelia, which gave high yields and had a 

good resistance to blight. The Amelia cultivar did not score very high in what the yield is 

concerned, but proved to be highly resistant to blight attack, which is a particularly 

important feature in organic farming (Table 1).. 

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Table 1. 

Results of tests on the suitability of potato cultivars in organic farming (Cojocna 

Cultivar Yield 

t/ha 

Average 

weight 

of a 

tuber 

(g) 

2004) 

Average 

No. of 

tubers/nest 

03.08.2004 

Degree of 

attack 

(%) 

01.09.2004 

Degree of 

attack 

(%) 

10.09.2004 

Degree of 

attack 

(%) 

Sante 36,4 45,9 17 10 30 80 

Tentant 34 58,1 14 60 90 90 

Robusta 28,5 54,0 11 10 10 70 

Redsec 24,6 51,3 10 10 70 80 

Frumoasa 24,4 52,4 10 50 90 90 

Rozal 21,7 57,4 8 10 30 80 

Roclas 17,6 50,3 7 80 90 90 

Agatha 17,2 54,2 7 90 90 90 

Amelia 16,7 49,6 7 10 30 80 

Dacia 13,2 34,3 8 20 90 90 

Christian 9,5 24,1 8 40 90 90 

Riviera 8,8 41,4 5 90 90 90 

10-30% – blight rezistant; 40-60% – blight rezistant; 60-90% – blight rezistant; 

5.1.5. The results regarding the suitability of a local potato cultivar assortment to 

biological agriculture, the average of years 2006-2008 

Experimental years 2006-2007-2008 were close in terms of friendliness to potato 

crops and similar from the climatic point of view. The obtained yields are similar 

between the three experimental years (Table 2), oscillating around 35-36 t / ha, with 

insignificant yield differences. 

The influence of experimental years on yield 

Table 2 

Year Yield(t/ha) % Difference Significance Duncan Test 

1. 2006 35,55 100,0 0.00 Mt. A 

2. 2007 35,56 100,0 0,01 - A 

3. 2008 34,68 97,5 -87 - A 

DL(p 5%) 1,47 

DL(p 1%) 2,23 

DL(p 0,1%) 3,58 

As an average over the three experimental years, the tested potato cultivars (Table 

3). can be grouped into two categories: the first category, represented by Robusta and 

11


Rozal cultivars, are varieties with less potential for high yields but more suitable to 

organic farming as a result of their higher resistance to blight, and the second category 

comprising the varieties with higher production potential (Redsec, Amelia and 

Productiv), which in the experimental years have exceeded the Robusta cultivar, 

considered as a control, by13 to 20% . These cultivars - Redsec, Amelia and Productiv 

gave significantly higher yields, over the three years, as compared with the Robusta 

variety, the differences being validated by statistical calculation performed through the 

multiple comparison test (Duncan). 

Table 3. 

The behaviour of the potato cultivars in the three experimental years 

Cultivar Yield(t/ha) % Difference Significance Duncan Test 

1. Robusta 32,20 100,0 0.00 Mt. A 

2. Rozal 31,48 97,8 -0,71 - A 

3. Redesec 38,63 120,0 6,44 *** B 

4. Amelia 36,57 113,6 4,38 *** B 

5. Productiv 37,44 116,3 5,25 *** B 

DL(p 5%) 2,15 

DL(p 1%) 2,88 

DL(p 0,1%) 3,80 

In the interaction experimental year x variety suitable to organic farming there are 

a variety of different behaviours of the cultivars over the experimental years (Table 4). 

Whereas in 2006 the varieties were almost equal to each other from the point of view of 

their yields, except for the Rozal cultivar which had a very strong decrease expressed by 

significant negative differences, in 2007 and 2008 all cultivars exceeded the variety 

Robusta , which was considered as a control. There seems to be an inverse correlation, 

which also occurs in the case of other crops such as wheat, corn, beets, etc., between 

production and quality. While the Robusta cultivar proved to be the most suitable variety 

for organic farming in terms of resistance to blight, its yields were lower than the other 

tested cultivars, considering the mean of the three years. 

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Tuber production in the interaction experimental year x cultivar 

Year Cultivar Yield 

(t/ha) 

% Difference 

(t) 

Significance Duncan 

Test 

2006 Robusta 36,91 100,0 0,00 Mt. DEF 

Rozal 28,14 76,2 -8,78 000 A 

Redsec 37,85 102,6 0,94 - EF 

Amelia 37,29 101,0 0,38 - EF 

Productiv 37,58 101,8 0,66 - EF 

2007 Robusta 30,10 100,0 0,00 Mt. AB 

Rozal 31,54 104,8 1,44 - ABC 

Redsec 38,19 126,9 8,09 *** EF 

Amelia 39,53 131,3 9,43 *** F 

Productiv 38,44 127,7 8,33 *** EF 

2008 Robusta 29,57 100,0 0,00 Mt. AB 

Rozal 34,77 117,6 5,20 ** CDE 

Redsec 39,85 134,8 10,28 *** F 

Amelia 32,90 111,3 3,33 - BCD 

Productiv 36,31 122,8 6,74 *** DEF 

DL (p 5%) 3,73 

DL (p 1%) 5,00 

DL (p 0,1%) 6,59 

5.2. 1 RESULTS ON THE EFFECTIVENESS OF NATURAL FOLIAR 

FERTILIZERS ON THE YIELD OF POTATO CULTIVARS 

Table 4. 

5.2.1 Results on the effectiveness of natural foliar fertilizers on the yield of potato 

cultivars, in 2004, in Cojocna, Cluj county 

. The way in which the foliar fertilizers influenced the yield of the year 2004 is 

shown in Table 5. 

Unfertilized cultivars reacted differently, by variable production increases, to 

foliar fertilizer application, and some even had a production decrease, most likely 

because of a metabolic block in the synthesis of starch, which is the case of the Sante 

cultivar, which reacted negatively to most foliar fertilization variants . Other varieties 

reacted positively to all products, such as Rozal, Dacia, Amelia, Riviera and Christian. 

These varieties are distinguished by statistically assured production increases, in most 

13


cases of foliar fertilization with the products used in our research. Except for Riviera, all 

cultivars are creations of the research activity in our country, which gives them an added 

advantage in the production of seed for potato organic production. 

In the new view upon the way of action of foliar fertilizers, they are assumed to 

have a big role in collecting the nutrients from the soil through increased absorption of 

mineral elements. From this point of view, the different cultivars may have a different 

response to foliar fertilization, as the genotype has or not a developed root system, or a 

higher/lower capacity of absorption of the nutrients in the soil. 

Among the tested varieties, we particularly noted the Rozal cultivar (in which 

production is significantly stimulated by four of the five tested foliar fertilizers), as well 

as the Amelia, Dacia, Riviera and Christian cultivars. 

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Cultivar Control Var.2 

The influence of the foliar fertilizers on the yield of the tested varieties (t/ha) (Cojocna 2004 ) 

Terra- 

Diff. to the 

control 

Var.3 

Glutaxin 

Diff. to 

the 

Var.4 

Maxiroot 

Diff. to 

the 

Var.5 

Biostar 

Diff. to 

the 

Var.6 

Amalgerol 

Sorb 

control 

control 

control 

control 

Tentant 34 33,5 -0,5 35,1 +1,1 38 +4 40,2 +6,2 30,3 -3,7 

Table5. 

Diff. to 

the 

Frumoasa 24,4 24,9 +0,5 21,1 -3,3 27,3 +2,9 17,2 -7,2 29,7 +5,3 

Robusta 28,5 26,0 -2,5 21,4 -7,1 29,9 +1,4 30,9 +2,4 36 +7,5 * 

Rozal 21,7 30,4 +8,7 * 

27,2 +5,5 39,3 +17,6 ** 

39,3 +17,6 ** 

Redsec 24,6 29,2 +4,6 30,9 +6,3 28 +3,4 39 +14,4 ** 

34,3 +12,6 * 

48,7 +24,1 ** 

Roclas 17,6 14,0 -3,6 12,3 -5,3 12,6 -5 19 +1,4 21,3 +3,7 

Dacia 13,2 19,6 +6,4 24,6 +11,4 * 

21,3 +8,1 * 

26,1 +12,9 * 

27,8 +14,6 ** 

Amelia 16,7 24,5 +7,8 * 

29,6 +12,9 * 

21,6 +5,6 25 +8,3 * 

24 +7,3 * 

Agatha 17,2 20,7 +3,5 19,6 +2,4 24,2 +7 20,4 +3,2 21,2 +4 

Riviera 8,8 21,2 +12,4 * 

13,1 +4,3 16,1 +7,3 * 

19,5 +10,7 * 

16,2 +7,4 * 

Sante 36,4 35,7 -0,7 34,4 -2 26 -10,4 0 

Christian 9,5 21,8 +12,3 * 

DL 5%=7,3 

DL1%=13,5 

DL0,1%=25,4 

25 +15,5 ** 

15 

14,2 +4,7 23,5 +14 ** 

37,8 +1,4 25,3 -11,1 0 

22,6 +13,1 *


5.2.2 Results on the effectiveness of natural foliar fertilizers on the yield of potato 

cultivars, the average of years 2006-2008, in Jucu, Cluj county 

As a result of the statistical calculations performed on the tuber yields resulting 

from the three years’ experiments in which different foliar fertilizer were applied to 

unfertilized potato plants, we noted very significant positive production differences. The 

production increases are between 3.79 and 5.71 t / ha or up to 18%, as compared with the 

unfertilized variant (Table 6).. 

Of the tested foliar fertilizers, Terra-Sorb stands out with significant differences as 

compared to Glutaxin, while the differences between the other foliar fertilizers are not 

significant, according to the Duncan test. 

Table 6. 

The influence of the foliar fertilizers on the tuber yield -Jucu, 2006-2008 

Foliar 

fertilizer 

Yield(t/ha) % Difference Significance Duncan Test 

no fertilizer 31,35 100,0 0,00 Mt. A 

Biomit 36,33 115,9 4,98 *** BC 

Biostar 36,10 115,2 4,75 *** BC 

Maxiroot 35,61 113,6 4,26 *** BC 

Terra Sorb 37,06 118,2 5,71 *** C 

Glutaxin 35,14 112,1 3,79 *** B 

DL(p 5%) 1,64 

DL(p 1%) 2,16 

DL(p 0,1%) 2,78 

Analyzing the average response of all tested potato cultivars, we noticed that there 

is a relationship of interdependence between some foliar fertilizers and the experimental 

year (Table 7). From this point of view, the year 2007 proved itself to be the most 

favourable one for applying this type of fertilizers; most variants gave very significant 

positive production differences, except for Glutaxin, for which the differences were 

distinctively significant positive.(CAMELIA SÎRBU et al, 2010). 

Production increases between 14 and 23% or 4.1 to 7.0 t / ha are worthy of 

consideration in any potato culture. In the experimental years 2006 and 2008, although 

production gains were achieved with all foliar fertilizers, the potato reacted differently, 

16


some fertilizers being more effective in 2006, others in 2008. However, what is a fact is 

that the natural foliar fertilizers allowed in organic farming can be an important source of 

production growth. 

Table 7. 

The influence of the foliar fertilizers on the tuber yields in the three experimental 

years 

Year Foliar Yield % Difference Significance Duncan 

treatment (t/ha) 

(t) 

Test 

2006 No fertilizer 32.16 100.0 0.00 Mt. ABC 

Biomit 35.33 110 3.17 * CDEFG 

Biostar 35.53 111 3.37 * DEFG 

Maxiroot 36.07 112 3.91 ** DEFG 

Terra Sorb 36.27 113 4.11 ** EFG 

Glutaxin 37.96 118 5.80 *** FG 

2007 No fertilizer 30.35 100.0 0.00 Mt. A 

Biomit 37.42 123 7.06 *** EFG 

Biostar 36.35 120 6.18 *** EFG 

Maxiroot 36.25 119 5.90 *** EFG 

Terra Sorb 38.26 126 7.91 *** 

G 

Glutaxin 34.54 114 4.19 ** BCDEF 

2008 No fertilizer 31.53 100.0 0.00 Mt. AB 

Biomit 36.24 115 4.71 ** EFG 

Biostar 36.25 115 4.71 ** EFG 

Maxiroot 34.50 109 2.97 * BCDE 

Terra Sorb 36.65 116 5.12 *** EFG 

Glutaxin 32.91 104 1.37 - ABCD 

DL (p 5%) 2.84 

DL (p 1%) 3.75 

DL (p 0,1%) 4.81 

In the interaction cultivar x foliar treatment, in the three experimental years (Table 

8.), the Robusta cultivar gave production increases with very significant differences as 

compared to the control when the Biostar fertilizer was applied, whereas, when the 

Biomit and Terra Sorb fertilizers were used, the differences were distinctively significant. 

When applying Glutaxin and Maxiroot, the yields were close to the unfertilized variant, 

the differences being of 1.30 t / ha, respectively 3.32 t / ha. 

17


Table 8. 

The influence of the foliar fertilizers on the tuber yields in experimental cultivars 

Cultivar Foliar Yield % Difference Significance Duncan Test 

Treatment (t/ha) 

(t) 

ROBUSTA No fertilizer 28.55 100.0 0.00 Mt. A 

Biomit 33.77 118 5.21 ** BCDEFG 

Biostar 35.18 123 6.62 *** DEFGHIJ 

Maxiroot 29.85 105 1.30 - AB 

Terra Sorb 33.96 119 5.41 ** BCDEFGH 

Glutaxin 31.87 112 3.32 - ABCDE 

ROZAL No fertilizer 28.39 100.0 0.00 Mt. A 

Biomit 32.09 113 3.70 * ABCDEF 

Biostar 30.16 106 1.77 - ABC 

Maxiroot 30.04 106 1.65 - AB 

Terra Sorb 34.48 122 6.09 ** CDEFGH 

Glutaxin 33.72 119 5.32 ** BCDEFG 

REDSEC No fertilizer 35.05 100.0 0.00 Mt. DEFGHIJ 

Biomit 42.97 123 7.92 *** M 

Biostar 37.80 108 2.75 - GHIJKL 

Maxiroot 37.87 108 2.85 - GHIJKL 

Terra Sorb 39.16 112 4.11 * 

IJKLM 

Glutaxin 38.95 111 3.90 * IJKLM 

AMELIA No fertilizer 33.62 100.0 0.00 Mt. BCDEFG 

Biomit 35.72 106 2.10 - EFGHIJ 

Biostar 35.28 105 1.66 - DEFGHIJ 

Maxiroot 40.18 120 6.56 *** KLM 

Terra Sorb 38.29 114 4.67 * HIJKL 

Glutaxin 36.35 108 2.72 - FGHIJK 

PRODUCTIV Nefertilizat 31.13 100.0 0.00 Mt. ABCD 

Biomit 37.09 119 5.96 ** GHIJK 

Biostar 42.10 135 10.97 *** LM 

Maxiroot 40.11 129 8.98 *** KLM 

Terra Sorb 39.42 127 8.29 *** JKLM 

Glutaxin 34.80 119 3.67 * DEFGHI 

DL (p 5%) 3.67 

DL (p 1%) 4.84 

DL (p 0,1%) 6.21 

The yields of the Rozal cultivar gave distinctively significant positive differences 

as compared to the control in the variants treated with Terra Sorb and Glutaxin, while in 

the variant treated with Biomit the differences were significant positive. 

18


The Redsec cultivar responded positively to the treatment with Biomit where the 

difference from the unfertilized variant was 7.92 t / ha, while in the case of Glutaxin and 

Terra Sorb, the differences from controls were 4.11 t / ha, respectively 3.90 t / ha. 

While the variants of Amelia cultivar on which fertilizers Biome, Biostar and 

Glutaxin were applied provided yields that were close to the unfertilized variant, with 

insignificant differences, the variants treated with Maxiroot and Terra Sorb gave yields 

with very significant, respectively significant differences to the control (Table 8). 

The Productiv cultivar is the only variety that accumulated production increases 

with foliar fertilizer application, the differences in production from the unfertilized 

variant ranging betweenn 3.67 t / ha and 10.97 t / ha. 

In conclusion, in the interaction variety x foliar treatment, the results of the three 

experimental years describe the Productiv cultivar as the most responsive to all foliar 

treatments (Table 8). The most effective products were found to be Biomit, with 

significant production gains in Robusta, Rozal Redsec and Productiv cultivars, and also 

Terra Sorb, in all the tested varieties. 

5.3. RESULTS ON THE EFFECTIVENESS OF SOME BLIGHT CONTROL 

NATURAL PRODUCTS 

Regarding blight control based on products supported by organic farming, the 

results were inconsistent from year to year and from variety to variety. However, some 

products should be taken into consideration for their effectiveness, namely those 

containing copper: the Bordeaux mixture, the copper oxy-chloride and the copper 

hydroxide. 

The cultivars in which the action of the Bordeaux mixture could not be clearly 

defined were Tentant, Agata şi Rivera (Fig. 7.). For all the other cultivars, the blight 

attack dicreased with 4 to 20% in comparison with the untreated control. 

19


Gradul de atac (%)/Attack degree(%) 

45 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Tentant 

Frumoasa 

Robusta 

Rozal 

Redsec 

Roclas 

Dacia 

Amelia 

Soiul/Variety Martor/Control 

Agata 

Riviera 

Fig.7. Blight control using Bordeaux mixture 

Sante 

Christian 

In the variant in which copper oxy-chloride was applied, only three cultivars had a 

significant positive reaction to the control, namely the Roclas cultivar, where the degree 

of attack decreased by 20% compared to the control and the Tentant and Robusta 

cultivars, where the degree of attack decreased by 10% compared to the untreated 

version. The other varieties had either a reaction with very close values to the control, or 

a neutral reaction (Fig. 8). 

Gradul de atac(%)/Attack degree(%) 

50 

45 

40 

35 

30 

25 

20 

15 

10 

5 

0 

Tentant 

Frumoasa 

Robusta 

Rozal 

Redsec 

Roclas 

Dacia 

Amelia 


Agata 

Riviera 

Fig. 8. Blight control using copper oxy-chloride 

Sante 

Christian 

In variant 8, where the treatment with copper hydroxide was applied, the cultivars 

that displayed a lower degree of blight attack were Tentant, Robusta, Roclas and Agata 

where it decreased by 10% compared to the control and the cultivars Riviera, Sante and 

20


Chiristian, which had a neutral reaction to the effect of copper hydroxide.(Fig. 9). The 

highest decrease of attack occurred in the variety Dacia, where it decreased by 20% 

compared to the untreated version. 

Gradul de atac(%)/Attack degree(%) 

60 

50 

40 

30 

20 

10 

0 

Tentant 

Frumoasa 

Robusta 

Rozal 

Redsec 

Roclas 

Dacia 

Amelia 


Agata 

Riviera 

Fig. 9. Blight control using copper hydroxide 

5.4 RESULTS REGARDING THE EFFECT OF NATURAL EXTRACTS IN 

COLORADO BEETLE (LEPTINOTARSA DECEMLINEATA SAY) 

CONTROL 

Sante 

Christian 

5.4.1. Results on the repellent effect of plant extracts on adult Colorado potato 

beetle, Cojocna 2004 

In order to analyse the possibility to control the Colorado Beetle by using natural 

plant extracts, a number of six products, in different concentrations were tested in 2004 in 

our experimental fields. The results are being presented in the following section. 

The results describing the effectiveness of the plant extracts in reducing the egg 

deposits laid by the Colorado beetle, Leptinotarsa decemlineata Say.,on the potato leaf, 

are presented in Table 9. 

In the control variant, untreated when the first egg deposits were laid, the average 

number of deposits was 1.5789/plant (with a minimum of 1.21egg deposits/plant at the 

third repetition and a maximum of 1.87 deposits /plant at the first repetition) 

In the variants that used extracts obtained from L. offinale Taraxacum (dandelion) 

and Tagetes erecta L. , alone or in combination, the efficacy in reducing the egg deposits 

21


of the Colorado beetle adults ranged from 46.74 % to 87.78%. These variants were 

reported to display between 0.8407 and 0.1930 egg deposits / plant. 

Table 9 

The efficacy of plant extracts in reducing the egg deposits of the Colorado beetle, 

Leptinotarsa decemlineata Say., Cojocna 2004 

Nr. 

Var. 

1 

2 

3 

4 

5 

6 

7 

Extract Conc. 

% 

Tagetes 

erecta 

Tagetes 

erecta 

Tagetes 

erecta + 

Taraxacum 

offinale 

Tagetes 

erecta + 

Taraxacum 

offinale 

Taraxacum 

offinale 

Taraxacum 

offinale 

Martor 

netratat 

12,50 

25,00 

5+5 

7+7 

12,50 

25,00 

- 

No. 

rep. 

Pl/ 

Rep. 

Egg 

dep./ 

rep. 

1 12 4 

2 15 6 

3 13 9 

4 12 9 

1 14 6 

2 11 3 

3 14 5 

4 10 6 

1 11 6 

2 12 10 

3 12 13 

4 9 8 

1 17 5 

2 18 4 

3 16 2 

4 11 6 

1 11 12 

2 14 4 

3 13 12 

4 12 5 

1 15 0 

2 16 3 

3 14 5 

4 12 3 

1 15 28 

2 14 25 

3 14 17 

4 14 20 

Pl./ 

var. 

52 

49 

44 

62 

50 

57 

57 

Egg 

deposits/ 

var. 

28 

20 

37 

17 

33 

11 

90 

Av. no. of 

egg 

deposits/pl 

0,5385 

0,4082 

0,8409 

0,2742 

0,6600 

0,1930 

1,5789 

E 

% 

65,89 

74,15 

46,74 

82,62 

5,19 

87,78 

In conclusion, plant extracts may be an alternative in the Colorado beetle control 

in potato crops, especially in fields in which production is expected to be organic. The 

extracts obtained from L. offinale Taraxacum (dandelion). and Tagetes erecta L. have a 

repellent effect on adults, which avoid to lay eggs on plants treated with these extracts. 

22 

0


The use of these extracts in combination may provide a synergy effect, which can 

increase the repellent effect. 

5.4.2. Results on the effect of hydro alcoholic extracts on Colorado potato beetle 

larvae, Cojocna 2004 

In controlling the Colorado beetle, we tested several plant extracts known to be 

potentially active on the larvae. The results describing the efficacy of these plant extracts 

in fighting the larvae of the species Leptinotarsa decemlineata Say. are given in Table 

10. 

The efficacy of plant extracts in controlling the Colorado beetle 

(Cojocna, 2004) 

Nr. 

Extract Concentration Larvae Efficacy % 

Var. 

% /plant 

1 Tagetes erecta L. 12,5 23,40 7,14 

2 Tagetes erecta L. 25 6,50 74,20 

3 Tagetes erecta L.+ Taraxacum officinale L. 5 + 5 20,00 20,64 

4 Tagetes erecta L.+ Taraxacum officinale L. 7 + 7 16,40 34,92 

5 Taraxacum officinale L. 12,5 13,40 46,83 

6 Taraxacum officinale L. 25 13,83 45,12 

7 Tagetes erecta L. 12,5 8,40 66,67 

8 Tagetes erecta L. 25 7,00 72,22 

9 Chrysanthemum cinerariaefolium Trev. 10 6,50 74,21 

10 Chrysanthemum cinerariaefolium Trev. 20 0,25 99,01 

11 Artemisia abrotanum L. 10 5,00 80,16 

12 Artemisia abrotanum L. 20 3,00 88,10 

13 Armoracia rusticana Lam. 10 6,66 73,57 

14 Armoracia rusticana Lam. 20 4,00 84,13 

15 Ruta corsica L. 10 8,75 65,28 

16 Ruta corsica L. 20 0,80 96,83 

17 Nepeta cataria var. citriodora 10 5,00 80,16 

18 Nepeta cataria var. citriodora 20 5,20 79,37 

19 Chrysanthemum balsamita var. canfora 10 7,50 70,24 

20 Chrysanthemum balsamita var. canfora 20 1,75 93,06 

21 Artemisia absinthium L. 10 19,00 24,60 

22 Leuzea carth. (herba) 10 5,60 77,78 

23 Leuzea carth. (herba) 20 6,40 74,60 

24 Artemisia capilaris 10 4,25 83,13 

25 Artemisia capilaris 20 3,80 84,92 

26 Marrubiumvulgaris L. 10 6,83 72,90 

27 Marrubium vulgaris L. 20 3,80 84,92 

28 Mentha piperita L. 10 6,75 73,21 

29 Martor netratat - 25,20 - 

23 

Table 10.


For the untreated control variant, the average number of larvae/plant was 25.2. In 

the variants where plant extracts made from Chrysanthemum cinerariaefolium Trev. 

Chrysanthemum balsamita var. canfora and Ruta corsica were used in a concentration of 

20%, the efficacy of the treatment was over 90% (99.01%; 93.06% and respectively 

96.83%). These efficacy rates are comparable to those obtained in the case of synthetic 

insecticides. In these variants the number of larvae/plant was between între 0.25 and 1.75, 

values that are below the economic damage threshold. When the same extracts were used 

in a concentration of 10%, the efficacy was 74.21% (6.5 larvae/plant), 70.24% (7.5 

larvae/plant) and respectively 65.28% (8.75 larvae/ plant). Also, at this concentration of 

the extract, older larvae, that were already on the plant when the treatment was applied, 

survived. Younger larvae, as well as those hatched after the application of the treatment 

were seriously affected (CAMELIA SÎRBU et all., 2004). 

For other extracts, the efficacy ranged between 80 –90% and, by repeated 

application, these extracts may provide acceptable results in obtaining ecological crops: 

Armoracia rusticana Lam. 20% (efficacy of 84.13%), Artemisia abrotanum L. 10% or 

20% (efficacy between 80.16 % and 88.10%), Artemisia capilaris, 10% or 20% (efficacy 

between 83.13% and 84.92%), Marrubium vulgaris L. 20% (efficacy of 84.92%) and 

Nepeta cataria var. citriodora with an efficacy of 80.16%. 

5.4.3. Results on the effect of hydro alcoholic extracts to control the Colorado potato 

beetle, Cojocna 2005 

In this year we tested extracts obtained from seven plants (Chrysanthemum 

cinerariaefolium Trev., Artemisia abrotanum L., Armoracia rusticana Lam., Ruta 

corsica L., Chrysanthemum balsamita var. Canfora, Artemisia capilaris şi Marrubium 

vulgaris L.)(Table 11.). 

For the untreated control variant, the average number of larvae/plant was 31.4. 

After applying a treatment based on plant extracts, the number of larvae decreased in all 

experimental variants, to values ranging between 5.25 (for Chrysanthemum 

cinerariaefolium Trev.) and 9.25 (for Marrubium vulgaris L.), which means decrease 

percentages of 70.5% and 83.3%. 

24


If we compare experimental data obtained this year with the previous year, the 

conclusion that can be drawn is that the use of these vegetal products to combat the 

larvae of Leptinotarsa decemlineata can significantly reduce the population of larvae. 

Since the use of plant extracts at the concentration of the previous year requires too much 

plant material (the previous year the proportion was 1: 1, which makes the method 

difficult to apply, this year we reduced the concentration of plant extract at a ratio of 1: 3. 

This decrease in concentration caused a decrease in the efficacy of biological plant 

extracts. Thus, for example, the effectiveness of Chrysanthemum cinerariaefolium 

Trev.în previous year was 99.01% (the best of experimental variants of 2004), and this 

year it decreased to 83.3%. For Marrubium vulgaris L. the efficacy of the previous year 

was 84.92%, and this year, by reducing the concentration of the extract, the efficacy went 

down to 70.5%. 

It is admitted that the efficacy of these products is strongly influenced by 

fluctuations in climatic factors (temperature, solar light and radiation), which can also 

have had an impact on the differences of effectiveness between the two experimental 

years. 

The efficacy of plant extracts in controlling the Colorado beetle, 2005 

No. 

Extract Concentratio Larvae Efficacy 

Var. 

n /plant % 

1 Chrysanthemum cinerariaefolium Trev. 1 : 3 5,25 83,3 

2 Artemisia abrotanum L. 1 : 3 7,75 75,3 

3 Armoracia rusticana Lam. 1 : 3 8,75 72,1 

4 Ruta corsica L. 1 : 3 6,25 80,0 

5 Chrysanthemum balsamita var. canfora 1 : 3 6,50 79,3 

6 Artemisia capilaris 1 : 3 8,50 72,9 

7 Marrubium vulgaris L. 1 : 3 9,25 70,5 

8 Martor netratat - 31,40 - 

Table 11 

The extracts from Chrysanthemum cinerariaefolium Trev. and Chrysanthemum 

balsamita var. canfora have a strong lethal effect in all variants. In variant 3, a 100% 

mortality of larvae was reported (Chrysanthemum balsamita var. canfora, at a ratio of de 

1:1), and in variant 2, the larval mortality was 95% (Chrysanthemum cinerariaefolium 

Trev. at a ratio of 1 :1). 

25


The plant extracts from Chrysanthemum cinerariaefolium Trev. obtained in 

propylene glycol (variants 9 and 10), although causing high mortality rate of larvae, still 

cannot be used, because of the phenomenon of phytotoxicity on treated plants. 

5.5. RESULTS REGARDING WEEDS CONTROL BY USING FIRE 

Among the known methods for weed control, the most common are: mechanical 

and manual hoeing, weeding, solarization, sowing simulation, etc., described in the 

introductory part of the thesis. 

One of modern methods for weed control in organic farming and applied more and 

more frequently in all potato producing countries is the use of fire. 

Most usually, potato crops in organic farming systems are weeded by the seed 

reserves in the manure used as main fertilizer. 

Using a device designed by us and manufactured in the didactic workshops of 

USAMV Cluj-Napoca, we experimented weed control in the field. The device uses liquid 

propane as a heat source and distributed in commercial tanks. The tanks are placed on a 

mobile cart on bicycle wheels that can be pulled among the rows and can be adjusted to 

the potato planting distance. 

By developing a culture system based on ”earthing up” the plant, we tried to 

protect the plants grown on the ridge of the ”hills” by creating a cone-shaped shield that 

directs the flame jet among the rows, thus protecting the leaves. Weed control by using 

fire can be done all over the surface of the crop before the emergence of potato plants, 

and after they grow, the device can be only used among the rows. 

Unlike the application of herbicides, when fire control is applied, weeds are 

affected totally regardless of the species. Destruction of weeds occurs by the action of 

high temperatures on cells, which explode by expansion of the water in them. The effect 

is immediate, visible in 15-20 min. and the weeds are irreversibly destroyed.. 

In our experiments, the weeds were destroyed by using fire at a cotyledonal stage+ 

one-two leaves (Fig.9), while at a more advanced stage we used the device among the 

26


rows, with the protection shield on(Fig. 10). The effect was total in both cases, the results 

being similar to those of manual hoeing (Fig. 11 and Fig. 12). 

Potato plants were affected to a lesser extent, and mainly on basal leaves that were 

already in an advanced stage of maturation, with early yellowing. 

The species of weeds we identified in the experimental field were: Convolvulus 

arvensis, Cirsium arvense, Symphytium officinale, Sonchus arvensis, Echinochloa crus- 

galli, Setaria glauca, Melandrium album, Poligonum convolvulus, Matricaria innodora, 

Cicorium intibus, Chenopodium album, Daucus carota. Among these, the dominant ones 

weret: Convolvulus arvensis, Cirsium arvense and Poligonum convolvulus. No species 

survived and none regenerated. 

Fig. 11. The effect of using fire for weed control (original) 

27


Fig. 12. The effect of using fire for weed control (original) 

28


CONCLUSIONS 

� Biological (organic) agriculture ensures healthy products without any toxic 

compounds, residues, pollutants or heavy metals; 

� From the Romanian national heritage we selected Robusta, Redsec, Rozalia and 

Amelia cultivars at the first stage, then completed the list by adding the Productiv 

cultivar, well- known for its high production potential and resistance to blight and 

viruses; 

� All the cultivars selected as suitable for organic farming provided, all over the 

research period, high yields (30 to 40 t / ha) and a high natural resistance to blight, 

with a degree of attack in early September between 20 and 65%, the Robusta 

variety proving to be the most resistant; 

� On average, for the three experimental years, the tested cultivars can be grouped 

into two categories: one comprising the varieties with medium production 

potential, such as Robusta and Rozal, but more favorable in terms of suitability to 

organic farming because of their natural resistance to blight, and another group 

that is made of Redsec, Amelia and Productiv with higher production potential and 

acceptable resistance to blight until early August; 

� With great consistency in production were noted the Redsec and Productiv 

varieties, known for their ecological plasticity, which makes them more valuable 

for the biological production system. Even though these varieties have some 

sensitivity to blight, their sustainability for organic production comes from the fact 

that blight can be controlled by using copper-based products, which are accepted 

in organic farming; 

� The reaction of the cultivars to foliar fertilization is different and this is 

determined by the role of the foliar fertilizers which, according to a new concept 

seem to stimulate the absorption of mineral elements from the soil, depending on 

the absorption capacity of the root system of each variety separately. This explains 

why some products have different effects on foliar different varieties; 

� Natural foliar fertilizers are an important source of production growth. The yield 

gain, as compared to the unfertilized control, can reach, in favourable years, 7 to 

10 t / ha; 

29


� In the interaction variety x foliar treatment, the results obtained over the three-year 

experiment show that Productiv is the most responsive cultivar to all foliar 

treatments. The most effective products were found to be Biomit, with significant 

increases in Robusta, Rozal, Redsec and Productiv, as well as Terra Sorb , with 

increases in all experimented varieties; 

� Natural foliar fertilizers influence the average tuber weight positively, with weight 

increases up to 18%. From this perspective the most effective proved to be Biomit 

and Biostar; 

� The research conducted for two years revealed the fact that the best cultivars were 

Robusta, Redsec, Amelia and Rozal, while, among the used products, the most 

effective ones were the Bordeaux mixture and the copper hydroxide, which can 

maintain foliage in vegetation for up to 60-70 days (August 1st); 

� The plant extracts obtained from the species Tagetes erecta and Taraxacum 

officinale, simple or mixed, in concentrations of 5, 12 or 25% can be an alternative 

control of Colorado beetles. These products showed repellent effects on adults, 

which avoid laying eggs on treated plants. 

� Using these natural extracts in combination, the repellent effect can be enhanced 

by synergistic action of both extracts; 

� The best results in controlling the larvae of the Leptinotarsa decemlineata Say. 

species were obtained by using the hydro-alcoholic extracts of Chrysanthemum 

cinerariaefolium Trev., Chrysanthemum balsamita var. canfora and Ruta corsica, 

all in concentrations of 20%.The efficacy of the treatment was 93 to 99%, which is 

comparable to the efficacy of synthetic insecticides. 

� The extracts of Chrysanthemum cinerariaefolium Trev. and Chrysanthemum 

balsamita var. Canfora, tested in the laboratory as well, have a strong lethal effect, 

in all variants 

� Promising results of 80% in the control of Colorado beetle larvae were also 

obtained with hydro-alcoholic extracts of horseradish (Armoracia rusticana), 

Artemisia abrotanum and Artemisia capilaris, Marrubium vulgaris and Nepeta 

cataria var. citrodora; 

30


� The use of fire in weed control can be considered an effective method and the 

results are similar to manual weeding. The potato plants were affected to a lesser 

extent, and mainly on basal leaves that were already in an advanced stage of 

maturation, with early yellowing. 

� The fire weed- control device designed by us can be used in biological potato 

crops 2-3 times until the potato plants cover the soil and the weeds cannot grow 

any longer because of the lack of light and, therefore, their influence on 

production is insignificant. 

31

Eng. SÎRBU CAMELIA MARIA (ALĂMOREAN) Ph D THESIS ...

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